Three-dimensional inkjet printing using ring-opening metathesis polymerization

ABSTRACT

Methods for fabricating three-dimensional objects by 3D-inkjet printing technology are provided. The methods utilize curable materials that polymerize via ring-opening metathesis polymerization (ROMP) in combination with toughening agents for fabricating the object. Systems suitable for performing these methods and kits containing modeling material formulations usable in the methods are also provided.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/075,652 filed on Aug. 5, 2018, which is a National Phase of PCTPatent Application No. PCT/IL2017/050138 having International FilingDate of Feb. 5, 2017, which claims the benefit of priority under 35 USC§ 119(e) of U.S. Provisional Patent Application Nos. 62/327,474 filed onApr. 26, 2016 and 62/291,625 filed on Feb. 5, 2016. The contents of theabove applications are all incorporated by reference as if fully setforth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates tothree-dimensional inkjet printing and, more particularly, but notexclusively, to systems, methods and compositions employing ring-openingmetathesis polymerization (ROMP) for producing three-dimensionalobjects.

Three-dimensional (3D) inkjet printing is a known process for buildingthree dimensional objects by selectively jetting chemical compositions,for example, polymerizable compositions, via ink jet printing headnozzles onto a printing tray in consecutive layers, according topre-determined image data. 3D inkjet printing is performed by a layer bylayer inkjet deposition of chemical formulations, which form together abuilding material formulation. Thus, a chemical formulation is dispensedin droplets from a dispensing head having a set of nozzles to formlayers on a receiving medium. The layers may then be cured or solidifiedusing a suitable methodology, to form solidified or partially solidifiedlayers of the building material.

The chemical formulations used for forming the building material may beinitially liquid and subsequently hardened (cured or solidified) to formthe required layer shape. The hardening may be effected, for example, byexposing the building material to a curing energy such as thermal energy(e.g., by heating the building material) or to irradiation (e.g., UV orother photo-irradiation), or may be activated chemically, for example,by acid or base activation.

The chemical (e.g., polymerizable) formulations utilized in inkjet 3Dprinting processes are therefore selected so as to meet the processrequirements, namely, exhibiting a suitable viscosity during jetting(thus being non-curable under jetting conditions) and rapid curing orsolidification, typically upon exposure to a stimulus, on the receivingmedium. For example, when used with currently available commercial printheads, the formulations should have a relatively low viscosity, of about10-25 cPs, at the jetting temperature, in order to be jettable.

Various three-dimensional printing techniques exist and are disclosedin, e.g., U.S. Pat. Nos. 6,259,962, 6,569,373, 6,658,314, 6,850,334,7,183,335, 7,209,797, 7,225,045, 7,300,619, 7,479,510, 7,500,846,7,962,237 and 9,031,680, all of the same Assignee, the contents of whichare hereby incorporated by reference.

In a 3D inkjet printing process such as Polyjet™ (Stratasys Ltd.,Israel), the building material is selectively jetted from one or moreprinting heads and deposited onto a fabrication tray in consecutivelayers according to a pre-determined configuration as defined by asoftware file.

A printing system utilized in a 3D inkjet printing process may include areceiving medium and one or more printing heads. The receiving mediumcan be, for example, a fabrication tray that may include a horizontalsurface to carry the material dispensed from the printing head. Theprinting head(s) may be, for example, an ink jet head having a pluralityof dispensing nozzles arranged in an array of one or more rows along thelongitudinal axis of the printing head. The jetting nozzles dispensematerial onto the receiving medium to create the layers representingcross sections of a 3D object.

In addition, there may be a source of curing energy, for curing thedispensed building material.

Additionally, the printing system may include a leveling device forleveling and/or establishing the height of each layer after depositionand at least partial solidification, prior to the deposition of asubsequent layer.

The building materials may include modeling materials and supportmaterials, which form the object and optionally the temporary supportconstructions supporting the object as it is being built, respectively.

The modeling material (which may include one or more material(s)) isdeposited to produce the desired object/s and the support material(which may include one or more material(s)) is used, with or withoutmodeling material elements, to provide support structures for specificareas of the object during building and assure adequate verticalplacement of subsequent object layers, e.g., in cases where objectsinclude overhanging features or shapes such as curved geometries,negative angles, voids, and so on.

Both the modeling and support materials are preferably liquid at theworking temperature at which they are dispensed, and subsequentlyhardened, upon exposure to a condition that affects curing of thematerials, to form the required layer shape. After printing completion,support structures are removed to reveal the final shape of thefabricated 3D object.

In order to be compatible with most of the commercially-availableprinting heads utilized in a 3D inkjet printing system, the uncuredbuilding material should feature the following characteristics: arelatively low viscosity (e.g., Brookfield Viscosity of up to 35 cps,preferably from 8 to 20 cps) at the working (e.g., jetting) temperature;Surface tension of from about 10 to about 50 Dyne/cm; and a Newtonianliquid behavior and high reactivity to a selected curing energy, toenable immediate solidification of the jetted layer upon activation(e.g., application of curing energy).

For example, a thin layer (5-40 microns) of the building material shouldbe sufficiently cured within about 200 milliseconds when exposed to UVradiation (of 0.5 W/cm², 340-390 nm), in order to enable the building ofsubsequent layers.

When a cured rigid modeling material forms the final object, the curedmaterial should preferably exhibit heat deflection temperature (HDT)which is higher than room temperature, in order to assure its usability.Typically, the cured modeling material should exhibit HDT of at least35° C. For an object to be stable in variable conditions, a higher HDTis desirable.

Currently, the most commonly used building materials in 3D inkjetprinting are photocurable, particularly, UV-curable materials such asacrylic based materials.

Currently available UV-curable modeling material formulations forforming rigid objects by inkjet printing which exhibit the propertiesrequired for 3D inkjet printing, while being jetted, as describedherein, are acrylic-based materials, which typically exhibit HDT in therange of 35-50° C. Exemplary such formulations are generally described,for example, in U.S. Pat. No. 7,479,510, to the present Assignee.

Such modeling material formulations, when cured, typically featureimpact resistance in the range of 20-25 J/m.

While rigid objects, or parts thereof, fabricated by 3D inkjet printing,should desirably exhibit good durability and stability, a cured modelingmaterial should feature both high HDT and high toughness, i.e., impactresistance.

Ring-opening metathesis polymerization (ROMP) is a type of olefinmetathesis chain-growth polymerization. The driving force of thereaction is the relief of strained cyclic structures, typically cyclicolefins (e.g., norbornenes or cyclopentenes) or dienes (e.g.,cyclopentadiene-based compounds). The polymerization reaction typicallyoccurs in the presence of organometallic catalysts, and the ROMPcatalytic cycle involves formation of metal-carbene species, whichreacts with the double bond in the cyclic structure to thereby form ahighly strained metallacyclobutane intermediate. The ring then opens,giving a linear chain double bonded to the metal with a terminal doublebond as well. The as formed metal-carbene species then reacts with thedouble bond on another cyclic monomer, and so forth.

During recent decades ROMP evolved as a powerful polymerization toolespecially due to the development of well-defined transition metalcomplexes as catalysts. Ruthenium, molybdenum and osmium carbenecomplexes useful as catalysts of ROMP reactions are described, forexample, in U.S. Pat. Nos. 5,312,940, 5,342,909, 5,728,917, 5,710,298,5,831,108, and 6,001,909; and PCT International Patent Applicationshaving Publication Nos. WO 97/20865, WO 97/29135 and WO 99/51344.

The use of ROMP reactions in reaction injection molding (RIM) has beendescribed, for example, in U.S. Patent Application Publication Nos.2011/0171147, 2005/0691432, U.S. Pat. No. 8,487,046, EP PatentApplication Publication No. 2452958, and EP Patent No. 2280017. One ofthe ROMP materials used in ROMP-based RIM is dicyclopentadiene (DCPD).

Poly-DCPD-based materials exhibit good mechanical properties and combineboth good toughness and high thermal resistance. For example, polymericmaterials based on DCPD were used to produce Telene 1810, which featuresa viscosity of about 200 cps at room temperature, HDT of 120° C. andimpact of 300 J/m; and Metton M15XX, which features a viscosity of 300cps at room temperature, Tg of 130° C. and impact of 460 J/m [see, forexample, www(dot)metton(dot)com/index(dot)php/metton-lmr/benefits].

Additional background art includes WO 2013/128452; Adv. Funct. Mater.2008, 18, 44-52; Adv. Mater. 2005, 17, 39-42; and Pastine, S. J.; Okawa,D.; Zettl, A.; Fréchet, J. M. J. J. Am. Chem. Soc. 2009, 131,13586-13587; Vidaysky and Lemcoff, Beilstein J. Org. Chem. 2010, 6,1106-1119; Ben-Asuly et al., Organometallics 2009, 28, 4652-4655;Piermattei et al., Nature Chemistry, DOI: 10.1038/NCHEM.167; Szadkowskaet al., Organometallics 2010, 29, 117-124; Diesendruck, C. E.; Vidaysky,Y.; Ben-Asuly, A.; Lemcoff, N. G., J. Polym. Sci., Part A: Polym. Chem.2009, 47, 4209-4213; Wang et al., Angew. Chem. Int. Ed. 2008, 47,3267-3270; U.S. Patent Application Publication No. 2009-0156766; WO2014/144634; EP Patent No. 1757613; U.S. Pat. No. 8,519,069; U.S. PatentApplication Publication No. 2005/0040564 and PCT InternationalApplication No. PCT/IL2015/051038 published as WO 2016/063282.

SUMMARY OF THE INVENTION

A need still exists for a 3D inkjet printing technology which employscurable materials that exhibit, upon curing, improved mechanicalperformance, particularly a combination of high thermal resistance andhigh toughness.

Ring Opening Metathesis Polymerization (ROMP) systems are used forproducing cured material that exhibit valuable properties, such asrelatively low shrinkage, high thermal resistance, high impact, andchemical and solvent resistance.

However, the ROMP technology is limited to methodologies such as, forexample, RIM, mainly due to its rapid curing at ambient conditions(e.g., room temperature). Typically, a formulation polymerizable by ROMPimmediately solidifies once a catalyst is added and/or activated. Thislimits the use of ROMP formulations in 3D inkjet processes, where liquidformulations that feature viscosity within a pre-determined range arerequired to be passed through inkjet printing heads.

The present inventors have now designed various methodologies whichenable using ROMP formulations in 3D inkjet printing.

Embodiments of the present invention therefore relate to formulationsand methods employing same which are designed for practicing ROMP-basedmethodologies while meeting the requirements of 3D inkjet printingprocesses, and while providing objects featuring exceptional mechanicalperformance.

According to an aspect of some embodiments of the present invention,there is provided a method of fabricating a three-dimensional object,the method comprising sequentially forming a plurality of layers in aconfigured pattern corresponding to the shape of the object, therebyforming the object, wherein the formation of each layer comprisesdispensing by at least one inkjet printing head at least one modelingmaterial formulation, the at least one modeling material formulationcomprising an unsaturated cyclic monomer polymerizable by ring openingmetathesis polymerization (ROMP), a catalyst for initiating ROMP of themonomer and a toughening agent (e.g., an impact modifying agent); andexposing the modeling material formulation to a condition for inducinginitiation of ROMP of the monomer by the catalyst, to thereby obtain acured modeling material.

According to some of any of the embodiments described herein, thetoughening agent is or comprises an elastomeric material.

According to some of any of the embodiments described herein, theelastomeric material is characterized by at least one of: a molecularweight lower than 30,000, or lower than 20,000, or lower than 10,000Daltons; being non-reactive towards ROMP; being dissolvable ordispersible in said at least one modeling material formulation; andbeing capable of forming a multiphase (e.g., biphasic) structure whenblended with said cured modeling material.

In some of the embodiments pertaining to the elastomeric material, theROMP monomer in the at least one modeling material formulation is orcomprises a DCPD or a derivative thereof.

According to some of any of the embodiments described herein, theelastomeric material is hydrophobic.

According to some of any of the embodiments described herein, theelastomeric material is a saturated polymeric material.

According to some of any of the embodiments described herein, theelastomeric material is characterized by: a molecular weight lower than30,000, or lower than 20,000, or lower than 10,000 Daltons; beingnon-reactive towards ROMP; being dissolvable or dispersible in said atlast one modeling material formulation; and being capable of forming amultiphase (e.g., biphasic) structure when blended with said curedmodeling material.

According to some of any of the embodiments described herein, theelastomeric material is a hydrophobic, saturated polymeric material, andin some of these embodiments, it has a molecular weight lower than30,000, or lower than 20,000 or lower than 10,000 Daltons.

According to some of any of the embodiments described herein, the atleast one modeling material formulation is characterized by a viscosity,of no more than 35 centipoises at a temperature of the inkjet printinghead during the dispensing.

According to some of any of the embodiments described herein, prior tothe exposing the catalyst does not initiate ROMP of the monomer.

According to some of any of the embodiments described herein, themodeling material formulation is such that the catalyst is activetowards initiating ROMP of the monomer, and wherein prior to theexposing, the catalyst and the monomer are physically separated in themodeling material formulation.

According to some of any of the embodiments described herein, thecondition comprises removing the physical separation between thecatalyst and the monomer.

According to some of any of the embodiments described herein, at leastone of the monomer and the catalyst is enveloped by a capsule and thecondition affects a release of the monomer or the catalyst from thecapsule.

According to some of any of the embodiments described herein, thecondition is selected from heat, irradiation, and shear forces.

According to some of any of the embodiments described herein, themodeling material formulation is such that the catalyst is inactivetowards initiating ROMP of the monomer.

According to some of any of the embodiments described herein, thecatalyst is activatable upon exposure to the condition.

According to some of any of the embodiments described herein, thecondition is selected from heat, and irradiation.

According to some of any of the embodiments described herein, theformulation further comprises an activator for chemically activating thecatalyst towards initiating ROMP of the monomer, and wherein prior tothe exposing, the activator is incapable of activating the catalyst.

According to some of any of the embodiments described herein, theactivator is physically separated from the catalyst and/or the monomerin the modeling material formulation.

According to some of these embodiments, the condition comprises removingthe physical separation between the activator and the catalyst and/orthe monomer.

According to some of any of the embodiments described herein, theactivator is enveloped by a capsule, and the condition affects a releaseof the activator from the capsule.

According to some of these embodiments, the condition is selected fromheat, irradiation, and shear forces.

According to some of any of the embodiments described herein, prior tothe exposing, the activator is chemically inactive in the modelingmaterial formulation.

According to some of any of the embodiments described herein, theactivator is activatable upon exposure to the condition, such thatexposing to the condition activates the activator, thereby activatingthe catalyst towards initiating ROMP of the monomer.

According to some of any of the embodiments described herein, themodeling material formulation further comprises a ROMP inhibitor.

According to some of any of the embodiments described herein, theunsaturated cyclic monomer comprises a chemical group polymerizable viaa non-ROMP reaction, and wherein the exposing further comprises exposingthe at least modeling material formulation to a condition for inducingpolymerization of the chemical group.

According to some of any of the embodiments described herein, the atleast one modeling material formulation further comprises at least onematerial polymerizable or curable via a non-ROMP reaction, and whereinthe exposing further comprises exposing the at least one modelingmaterial formulation to a condition for inducing polymerization orcuring of the at least one material.

According to some of any of the embodiments described herein, theadditional curable material comprises a monomer and/or an oligomerpolymerizable by free-radical polymerization, cationic polymerization,anionic polymerization, or polycondensation.

According to some of any of the embodiments described herein, theadditional curable material is polymerizable or curable upon exposure toirradiation (photopolymerizable).

According to some of any of the embodiments described herein, theadditional curable (polymerizable) material and the unsaturated cyclicmonomer polymerizable by the ROMP are included in the same modelingmaterial formulation.

According to some of any of the embodiments described herein, at leastone of the non-ROMP polymerizable or curable material, an initiator ofthe non-ROMP reaction, the monomer polymerizable by the ROMP, and thecatalyst is physically separated from other components in theformulation.

According to some of any of the embodiments described herein, theformation of each layer comprises dispensing at least two modelingmaterial formulations by at least two inkjet printing heads, each headjetting one of the at least two modeling material formulations.

According to some of any of the embodiments described herein, at leastone of the modeling material formulations comprises the unsaturatedcyclic monomer polymerizable by ROMP, and at least another one of themodeling material formulations comprises the catalyst.

According to some of any of the embodiments described herein, at leastone of the modeling material formulations which comprises the monomerpolymerizable by ROMP further comprises an activator for chemicallyactivating the catalyst towards initiating ROMP of the monomer.

According to some of any of the embodiments described herein, at leastone of the modeling material formulations comprises the unsaturatedcyclic monomer polymerizable by ROMP, and the catalyst, and at leastanother one of the modeling material formulations comprises an activatorfor chemically activating the catalyst towards initiating ROMP of themonomer.

According to some of any of the embodiments described herein, thematerial polymerizable or curable by the non-ROMP reaction (theadditional curable material) is comprised in at least one modelingmaterial formulation which is devoid of the monomer polymerizable by theROMP.

According to some of any of the embodiments described herein, at leastone of the modeling material formulations further comprises an initiatorof the non-ROMP reaction.

According to some of any of the embodiments described herein, theinitiator is comprised in at least one modeling material formulationwhich is devoid of the material polymerizable or curable via thenon-ROMP reaction.

According to some of any of the embodiments described herein, thecondition for inducing ROMP of the unsaturated cyclic monomer and thecondition for inducing polymerization or curing of the chemical group ormaterial polymerizable or curable via a non-ROMP reaction are the same.

According to some of any of the embodiments described herein, theformation of each layer comprises dispensing at least two modelingmaterial formulations by at least two inkjet printing heads, each headjetting one of the at least two modeling material formulations, whereinat least two of the modeling material formulations independentlycomprise the unsaturated cyclic monomer polymerizable by ROMP, andwherein at least one of the modeling material formulations comprises thecatalyst.

According to some of any of the embodiments described herein, at leastone of the modeling material formulations comprises the monomer and thecatalyst.

According to some of any of the embodiments described herein, thecatalyst is activatable by the condition.

According to some of any of the embodiments described herein, thecatalyst is activatable by an activator, and at least one of themodeling material formulations comprises the activator and is devoid ofthe catalyst.

According to some of any of the embodiments described herein, at leastone of the formulations comprises the monomer and the activator and atleast another one of the formulations comprises the monomer and thecatalyst.

According to some of any of the embodiments described herein, at leastone of the formulations comprises a ROMP inhibitor.

According to some of any of the embodiments described herein, whenevertwo or more modeling material formulations are used, a toughening agentas described herein is included in one, two or each of the modelingmaterial formulations.

According to some of any of the embodiments described herein, the atleast one modeling material formulation further comprises a stabilizingagent, a surface active agent, an elastomeric component or composition,and an antioxidant, a filler, a pigment, and a dispersant.

According to some of any of the embodiments described herein, the methodfurther comprises dispensing a support material formulation by at leastone additional inkjet printing head.

According to some of any of the embodiments described herein, the methodfurther comprises exposing the support material formulation to acondition for inducing polymerization or curing of the support materialformulation.

According to some of any of the embodiments described herein, atemperature of an inkjet printing head for dispensing the at least onemodeling material formulation ranges from 25° C. to 65° C.

According to some of any of the embodiments described herein, atemperature of an inkjet printing head for dispensing the at least onemodeling material formulation ranges from 65° C. to about 85° C.

According to some of any of the embodiments described herein, thecondition is heat and wherein the exposing to the condition comprisesheating the at least one modeling material formulation following thedispensing.

According to some of any of the embodiments described herein, theheating is by infrared radiation.

According to some of any of the embodiments described herein, theheating is by a ceramic radiation source.

According to some of any of the embodiments described herein, thedispensing is in a chamber, and wherein the heating comprises heatingthe chamber to a temperature of from 25° C. to 65° C.

According to some of any of the embodiments described herein, theplurality of layers are formed on a working tray, the method comprisingheating the working tray to a temperature of from 25° C. to 65° C.

According to some of any of the embodiments described herein, thedispensing and/or the exposing are performed under inert atmosphere.

According to some of any of the embodiments described herein, the methodfurther comprises straightening the layer by a leveling device.

According to some of any of the embodiments described herein, the methodfurther comprises removing cured or partially cured formulation off theleveling device.

According to some of any of the embodiments described herein, thestraightening is while the at least one formulation is at a cured orpartially cured state.

According to some of any of the embodiments described herein, thestraightening comprises milling.

According to an aspect of some embodiments of the present invention,there is provided a system for three-dimensional inkjet printing, asdescribed herein.

Further according to any one of the embodiments of the presentinvention, there are provided kits comprising one or more of themodeling material formulations as described herein in any of therespective embodiments, which, in some embodiments, are usable in themethods as described herein.

Further according to any one of the embodiments of the presentinvention, there are provided three-dimensional objects obtainable bythe methods as described herein.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

Implementation of the method and/or system of embodiments of theinvention can involve performing or completing selected tasks manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of embodiments of the method and/or systemof the invention, several selected tasks could be implemented byhardware, by software or by firmware or by a combination thereof usingan operating system.

For example, hardware for performing selected tasks according toembodiments of the invention could be implemented as a chip or acircuit. As software, selected tasks according to embodiments of theinvention could be implemented as a plurality of software instructionsbeing executed by a computer using any suitable operating system. In anexemplary embodiment of the invention, one or more tasks according toexemplary embodiments of method and/or system as described herein areperformed by a data processor, such as a computing platform forexecuting a plurality of instructions. Optionally, the data processorincludes a volatile memory for storing instructions and/or data and/or anon-volatile storage, for example, a magnetic hard-disk and/or removablemedia, for storing instructions and/or data. Optionally, a networkconnection is provided as well. A display and/or a user input devicesuch as a keyboard or mouse are optionally provided as well.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 is a flowchart describing an exemplary method according to someembodiments of the present invention;

FIG. 2 is a schematic illustration of a system suitable for 3D inkjetprinting of an object according to some embodiments of the presentinvention;

FIGS. 3A-3C are schematic illustrations of printing heads according tosome embodiments of the present invention; and

FIG. 4 is a schematic illustration of a self-cleaning leveling device,according to some embodiments of the present invention.

FIGS. 5A and 5B present schematic illustrations of bitmaps inembodiments of the invention in which a “Drop on Drop” printing protocolis employed. A bitmap suitable for the deposition of the first modelformulation is illustrated in FIG. 5A and a bitmap suitable for thedeposition of the second model formulation is illustrated in FIG. 5B.When the droplets of both formulations have the same or approximatelythe same weight, the bitmaps are useful for a 50:50 (or 1:1) w/w ratio.White boxes represent vacant locations, dotted boxes represent dropletsof the first model formulation and wavy boxes represent droplets of thesecond model formulation. Each patterned (wavy/dotted) box represents apixel (e.g., one composition droplet) in a layer. Both modelformulations can be deposited at the same location, but at differenttimes, during movement of the printing heads.

FIGS. 6A and 6B present schematic illustrations of bitmaps inembodiments of the invention in which a “side-by-side” printing protocolis employed. A bitmap suitable for the deposition of the first modelformulation is illustrated in FIG. 6A and a bitmap suitable for thedeposition of the second model formulation is illustrated in FIG. 6B.When the droplets of both formulations have the same or approximatelythe same weight, the bitmaps are useful for a 50:50 (or 1:1) w/w ratio.White boxes represent vacant locations, dotted boxes represent dropletsof the first model formulation and wavy boxes represent droplets of thesecond model formulation. Each patterned (wavy/dotted) box represents apixel (e.g., one formulation droplet). A drop of the first modelformulation (dotted boxes) is deposited adjacent to a drop of the secondmodel formulation (wavy boxes). Both model formulations may be depositedsimultaneously during movement of the printing heads.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates tothree-dimensional inkjet printing and, more particularly, but notexclusively, to systems, methods and compositions employing ring-openingmetathesis polymerization (ROMP) for producing three-dimensionalobjects.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings and/or the Examples. The invention iscapable of other embodiments or of being practiced or carried out invarious ways.

The present inventors have sought for methodologies that enableutilizing materials obtained via ring opening metathesis polymerization(ROMP) in three-dimensional (3D) inkjet printing processes.

As discussed hereinabove, 3D inkjet printing systems require, on onehand, using building material formulations which exhibit certainproperties while being dispensed from inkjet printing heads, and, on theother hand, aim to obtain three-dimensional objects which featurestability, durability and toughness.

Most of the currently available 3D inkjet printing processes utilizephotocurable (e.g., UV curable) formulations. These formulations, whilemeeting the requirements of suitable viscosity at the jettingtemperature and a rapid hardening upon exposure to irradiation, oftenprovide objects with mechanical properties that are less than desired.

Materials obtained by ring-opening metathesis polymerization (ROMP) arecharacterized by exceptional mechanical and other properties. However,employing ROMP chemistry in 3D inkjet printing requires solving problemsassociated with, for example, fast propagation of the polymerizationreaction, immediately once a catalyst contacts a ROMP monomer. Thus, forexample, pre-mixing a ROMP monomer and a ROMP catalyst before jettingleads to substantial increase in viscosity when such a formulationpasses through the inkjet printing head and nozzle plate, resulting inclogging due to polymerization of the composition on the nozzle plate.

The present inventors have now designed and successfully practiced novelmethodologies for utilizing the valuable properties of materialsprepared by ROMP in the fabrication of three-dimensional objects in 3Dinkjet printing processes.

The Method:

According to aspects of some embodiments of the present invention, thereis provided a method of three-dimensional (3D) inkjet printing of athree-dimensional object. According to embodiments of these aspects, themethod is effected by sequentially forming a plurality of layers in aconfigured pattern corresponding to the shape of the object, therebyforming the object.

According to embodiments of these aspects, formation of each layer iseffected by dispensing at least one building material formulation(uncured building material), and exposing the dispensed buildingmaterial formulation to condition which affect curing of the formulationto thereby obtain a cured building material.

The method and system of the present embodiments manufacturethree-dimensional objects based on computer object data in a layerwisemanner by forming a plurality of layers in a configured patterncorresponding to the shape of the objects. The computer object data canbe in any known format, including, without limitation, a StandardTessellation Language (STL) or a StereoLithography Contour (SLC) format,Virtual Reality Modeling Language (VRML), Additive Manufacturing File(AMF) format, Drawing Exchange Format (DXF), Polygon File Format (PLY)or any other format suitable for Computer-Aided Design (CAD).

Each layer is preferably formed by three-dimensional inkjet printingwhich scans a two-dimensional surface and patterns it. While scanning,the apparatus visits a plurality of target locations on thetwo-dimensional layer or surface, and decides, for each target locationor a group of target locations, whether or not the target location orgroup of target locations is to be occupied by building material, andwhich type of building material is to be delivered thereto. The decisionis made according to a computer image of the surface.

When three-dimensional inkjet printing is employed, a building material(uncured) is dispensed from a dispensing head having a set of nozzles todeposit the building material in layers on a supporting structure. Theinkjet printing system thus dispenses building material in targetlocations which are to be occupied and leaves other target locationsvoid. The inkjet printing typically includes a plurality of dispensingheads, each of which can be configured to dispense a different buildingmaterial formulation. Thus, different target locations can be occupiedby different building materials.

The types of building materials can be categorized into two majorcategories: modeling material and support material. The support materialserves as a supporting matrix or construction for supporting the objector object parts during the fabrication process and/or other purposes,e.g., providing hollow or porous objects. Support constructions mayadditionally include modeling material elements, e.g. for furthersupport strength.

Herein throughout, the phrases “building material formulation”, “uncuredbuilding material”, “uncured building material formulation”, “buildingmaterial” and other variations therefore collectively describe thematerials that are dispensed to sequentially form the layers, asdescribed herein. This phrase encompasses uncured materials dispensed soas to form the object, namely, one or more uncured modeling materialformulation(s), and uncured materials dispensed so as to form thesupport, namely uncured support material formulations.

Herein throughout, the term “object” describes a final product of theadditive manufacturing. This term refers to the product obtained by amethod as described herein, after removal of the support material, ifsuch has been used as part of the uncured building material. The“object” therefore essentially consists (e.g., at least 95 weightpercents) of a cured modeling material.

The term “object” as used herein throughout refers to a whole object ora part thereof.

Herein, the phrase “printed object” describes the product of the 3Dinkjet process, before the support material, if such has been used aspart of the uncured building material, is removed.

Herein throughout, the phrase “cured modeling material” describes thepart of the building material that forms the object, as defined herein,upon exposing the dispensed building material to curing (and optionallypost-treatment), and, optionally, if a support material has beendispensed, removal of the cured support material, as described herein.The cured modeling material can be a single cured material or a mixtureof two or more cured materials, depending on the modeling materialformulations used in the method, as described herein.

The phrase “cured modeling material” or “cured modeling materialformulation” can be regarded as a cured building material wherein thebuilding material consists only of a modeling material formulation (andnot of a support material formulation). That is, this phrase refers tothe portion of the building material, which is used to provide the finalobject.

Herein throughout, the phrase “modeling material formulation”, which isalso referred to herein interchangeably as “modeling formulation”,“modeling material” “model material” or simply as “formulation”,describes a part or all of the uncured building material which isdispensed so as to form the object, as described herein. The modelingmaterial formulation is an uncured modeling formulation (unlessspecifically indicated otherwise), which, upon exposure to a conditionthat effects curing, forms the object or a part thereof.

In some embodiments of the present invention, a modeling materialformulation is formulated for use in three-dimensional inkjet printingand is able to form a three-dimensional object on its own, i.e., withouthaving to be mixed or combined with any other substance.

An uncured building material can comprise one or more modelingformulations, and can be dispensed such that different parts of theobject are made, upon curing, of different cured modeling formulations,and hence are made of different cured modeling materials or differentmixtures of cured modeling materials.

The method of the present embodiments manufactures three-dimensionalobjects in a layerwise manner by forming a plurality of layers in aconfigured pattern corresponding to the shape of the objects, asdescribed herein.

The printed three-dimensional object is made of the modeling material ora combination of modeling materials or a combination of modelingmaterial/s and support material/s or modification thereof (e.g.,following curing). All these operations are well-known to those skilledin the art of solid freeform fabrication.

In some exemplary embodiments of the invention an object is manufacturedby dispensing a building material that comprises two or more differentmodeling material formulations, each modeling material formulation froma different dispensing head of the inkjet printing apparatus. Themodeling material formulations are optionally and preferably depositedin layers during the same pass of the printing heads. The modelingmaterial formulations and/or combination of formulations within thelayer are selected according to the desired properties of the object.

FIG. 1 presents a flowchart describing an exemplary method according tosome embodiments of the present invention. It is to be understood that,unless otherwise defined, the operations described hereinbelow can beexecuted either contemporaneously or sequentially in many combinationsor orders of execution. Specifically, the ordering of the flowchart isnot to be considered as limiting. For example, two or more operations,appearing in the following description or in the flowchart diagrams in aparticular order, can be executed in a different order (e.g., a reverseorder) or substantially contemporaneously. Additionally, severaloperations described below are optional and may not be executed.

The method begins at 10 and optionally and preferably continues to 11 atwhich 3D printing data corresponding to the shape of the object arereceived. The data can be received, for example, from a host computerwhich transmits digital data pertaining to fabrication instructionsbased on computer object data, e.g., in a form of a StandardTessellation Language (STL) or a StereoLithography Contour (SLC) format,Virtual Reality Modeling Language (VRML), Additive Manufacturing File(AMF) format, Drawing Exchange Format (DXF), Polygon File Format (PLY)or any other format suitable for Computer-Aided Design (CAD).

The method continues to 12 at which droplets of a building material asdescribed herein are dispensed in layers, on a receiving medium, usingat least two different multi-nozzle inkjet printing heads, according tothe printing data. The receiving medium can be a tray of athree-dimensional inkjet system or a previously deposited layer. Thebuilding material comprises one or more modeling material formulationsthat can undergo polymerization via ROMP, as described herein. Thebuilding material cam optionally further comprise a support materialformulation.

In some embodiments of the present invention, the dispensing 12 iseffected within an environment that is similar in its thermodynamiccondition (for example, temperature, humidity, pressure) to the ambientenvironment. Alternatively, the dispensing 12 can be executed in agenerally dry (e.g., relative humidity of less than 60% or less than 50%or less than 40%, or less) and inert environment. For example, thedispensing can be executed in a nitrogen environment. In theseembodiments, dispensing 12 is executed in a chamber and is optionallyand preferably preceded by an operation in which an inert gas, e.g.,nitrogen, helium, krypton and the like is introduced into the chamber.

Optionally, before being dispensed, the uncured building material, or apart thereof (e.g., one or more formulations of the building material),is heated, prior to being dispensed. These embodiments are particularlyuseful for uncured building material formulations having relatively highviscosity at the operation temperature of the working chamber of a 3Dinkjet printing system. The heating of the formulation(s) is preferablyto a temperature that allows jetting the respective formulation througha nozzle of a printing head of a 3D inkjet printing system. In someembodiments of the present invention, the heating is to a temperature atwhich the respective formulation exhibits a viscosity of no more than Xcentipoises, where X is about 40 centipoises, or about 35 centipoises,or about 30 centipoises, preferably about 25 centipoises and morepreferably about 20 centipoises, or 18 centipoises, or 16 centipoises,or 14 centipoises, or 12 centipoises, or 10 centipoises and even as lowas 2 centipoises.

The heating can be executed before loading the respective formulationinto the printing head of the 3D printing system, or while theformulation is in the printing head or while the formulation passesthrough the nozzle of the printing head.

In some embodiments, the heating is executed before loading of therespective formulation into the printing head, so as to avoid cloggingof the printing head by the formulation in case its viscosity is toohigh.

In some embodiments, the heating is executed by heating the printingheads, at least while passing the formulations making up the buildingmaterial through the nozzle of the printing head.

In some embodiments, a temperature of an inkjet printing head fordispensing a modeling material formulation as described herein is lowerthan 70° C., and ranges, for example, from about 25° C. to about 65° C.,including any subranges and intermediate values therebetween. Modelingmaterial formulations which comprise one or more monomers that undergopolymerization via ROMP, as described herein, and optionally other,non-curable components, are suitable for use in the context of theseembodiments.

In some embodiments, higher temperatures of an inkjet printing head arerequired, for example, higher than 70° C., or ranging from about 65° C.to about 95° C., or from about 65° C. to about 85° C., including anysubranges and intermediate values therebetween. Modeling materialformulations which comprise curable materials which are polymerizable bynon-ROMP reactions, as described herein (for example, UV-curableacrylates and methacrylates, and/or epoxy monomers useful for cationicphotopolymerization), as curable components, optionally in addition toROMP-curable components, are suitable for use in the context of theseembodiments.

Once the uncured building material is dispensed on the receiving mediumaccording to the 3D printing data, the method optionally and preferablycontinues to 13 at which the deposited layers are exposed to a condition(or two or more conditions) that induces ROMP, as defined herein.Preferably, each individual layer is exposed to this condition followingor during the deposition of the layer, and prior to the deposition ofthe subsequent layer.

In some embodiments, exposing to conditions that effect curing isperformed under a generally dry and inert environment, as describedherein.

In these embodiments, the dry and inert environment is optionally andpreferably prepared before the material is dispensed so that 13 can beexecuted simultaneously with 12 wherein the material is exposed to theenvironment upon exiting the inkjet printing head.

Alternatively, the exposure 13 can include exposing the dispensed layerto radiation, such as, but not limited to, electromagnetic radiation,for example, infrared radiation (e.g., at a wavelength of from about 800nm to about 4 μm), ultraviolet radiation (e.g., at a wavelength of fromabout 200 nm to about 400 nm) and visible or near-visible lightradiation (e.g., at a wavelength of from about 400 nm to about 800 nm),or particle radiation, for example in the form of an electron beam,depending on the modeling material being used. Preferably, but notnecessarily, the infrared radiation is applied by a ceramic lamp, forexample, a ceramic lamp that produces infrared radiation of from about 3μm to about 4 μm, e.g., about 3.5 μm, or of any other wavelengthsuitable for efficient application of heat, as discussed hereafter.Alternatively or additionally, the exposure 13 can include exposing thedispensed layer to elevated temperature (for example, from about 25° C.to about 100° C., or from about 25° C. to about 65° C., or from about65° C. to about 100° C.). Higher temperatures (for example, above 100°C. or from about 100° C. to about 900° C., or from about 200° C. toabout 900° C., e.g., about 300° C., or from about 300° C. to about 900°C. or from about 400° C. to about 900° C.) are also contemplated. Theelevated temperatures can be generated by heating the tray on which thelayers are dispensed, and/or the chamber within which the printingprocess is executed or heat-inducing irradiation, using a radiationsource as described herein, at a suitable wavelength for providing arequired temperature. A ceramic lamp, for example, when operated at theabove-described wavelengths, may result in heating a dispensedformulation to up to 300° C., and even to a temperature of from about400° C. to about 900° C.

The method can preferably continue to 14 at which the deposited layer isstraightened, for example, by a leveling device. Optionally, the layeris straightened after the dispensed formulation is cured. Alternatively,the layer is straightened while the dispensed formulation is stilluncured. In some embodiments, straightening of a layer is performed soas to provide a certain (e.g., pre-determined) thickness of the layer,to thereby provide a plurality of layers in which a thickness of atleast one, and preferably two or more, of the layers is controlled.

As used herein the phrase “cured” refers to a formulation that underwentcuring or at least a partial curing, as defined herein, and encompassesa state of the formulation in which at least 20% or at least 30% or atleast 40% or at least 50% or at least 60% or at least 70% of theformulation underwent curing, as defined herein, and a state of aformulation that underwent up to 100% curing.

Typically, a formulation that underwent curing or partial curing ischaracterized by a viscosity that is substantially higher than anuncured formulation, and preferably, a formulation, or at least a partthereof, solidifies upon curing. A “cured” formulation is also referredto interchangeably as a “hardened” formulation or as a “solidified”formulation.

Straightening or leveling of a layer or layers after curing (or partialcuring) can be achieved by a leveling device that is capable ofreforming the solidified portion of the formulation or removing partthereof. A representative example of such a leveling device is a rollercapable of milling, grinding and/or flaking a solidified formulation orpart thereof. Straightening can be achieved by a leveling device that iscapable of leveling the formulation in its liquid, gel, partially curedor cured state.

In some embodiments, the leveling device effects milling, grindingand/or flaking, and/or removes at least part of the top of a layer ofthe formulation. Such a leveling device can be, for example, a roller, ablade or cutter.

In some embodiments of the present invention the method continues to 15at which cured or partially cured or uncured formulation is removed offthe leveling device. These embodiments are particularly useful when theleveling device is applied to the layer while the formulation is uncuredor partially cured. In this case, a portion of the formulation collectedby the leveling device can experience curing or partial curing while theformulation is on the leveling device (for example on the roller, whenthe leveling device comprises a roller), and the method preferablyremoves that cured or partially cured formulation from the device. Theseembodiments can also be useful when the leveling device is applied tothe layer while the formulation is cured (for example, when the levelingdevice effects milling, grinding, flaking and/or removing part of thesolidified portion of the formulation). In this case the method removesthe debris of the milling, grinding, flaking or material removal processfrom the leveling device, using for example a suction device.

Operation 15 is preferably executed automatically and optionally alsocontinuously while the leveling device is in motion over the layer. Forexample, the leveling device can comprise a double roller having a firstroller that contacts and straightens the layer and a second that is incontact with the first roller but not with the layer and which isconfigured to remove the formulation from the first roller.

The method ends at 16.

In some of any of the embodiments described herein, the buildingmaterial comprises one or more modeling material formulations, asdescribed in further detail hereinafter, and dispensing the buildingmaterial comprises dispensing one or more modeling materialformulations.

To ensure reaction between the first and second modeling materialformulations, the deposition of the compositions can be performed inmore than one way.

In some embodiments of the present invention a “Drop on Drop” printingprotocol is employed. These embodiments are schematically illustrated inFIGS. 5A and 5B. A bitmap suitable for the deposition of the firstmodeling material formulation is illustrated in FIG. 5A and a bitmapsuitable for the deposition of the second modeling material formulationis illustrated in FIG. 5B. White boxes represent vacant locations,dotted boxes represent droplets of the first modeling materialformulation and wavy boxes represent droplets of the second modelingmaterial formulation. The printing data in these embodiments are suchthat for each layer, both modeling material formulations are depositedat the same location, but different times, during movement of theprinting head. For example, each droplet of a first modeling materialformulation can be jetted on top of a droplet of a second modelingmaterial formulation, or vice versa. Preferably, but not necessarily,the two formulation parts are jetted in drops at the same weight and/orrate. These embodiments are particularly useful when the desired weightratio is 1:1. For other desired weight ratios, the two formulation partsare preferably jetted in drops of different weights, wherein the ratioof the weights corresponds to the desired ratio.

A representative example for a resolution suitable for the presentembodiments is 1200 dpi in the X direction and 300 dpi in the Ydirection. The drop on drop printing protocol allows the two types ofdrops to combine and mix before the crystallization of depositedmaterial.

In some embodiments of the present invention a “side by side” printingprotocol is employed. These embodiments are schematically illustrated inFIGS. 6A and 6B. A bitmap suitable for the deposition of the firstmodeling material formulation is illustrated in FIG. 6A and a bitmapsuitable for the deposition of the second modeling material formulationis illustrated in FIG. 6B. The colors of the white, dotted and wavyboxes represent vacant locations, droplets of the first modelingmaterial formulation and droplets of the second modeling materialformulation, respectively. The printing data in these embodiments issuch that for each layer, each drop of a first modeling materialformulation is jetted adjacent to a drop of a second modeling materialformulation, or vice versa. Due to drop spreading, the adjacent dropstend to partially overlap. As a result, the two drops diffuse towardeach other, mix and interact after deposition.

In the schematic illustrations shown in FIGS. 5A-6B, chessboard bitmapsare illustrated, but this need not necessarily be the case, since, forsome applications, other bitmap patterns can be employed.

In some of any of the embodiments described herein, the buildingmaterial further comprises one or more support material formulations.

In some of any of the embodiments described herein, dispensing abuilding material further comprises dispensing the support materialformulation(s).

Dispensing the support material formulation, in some embodiments, iseffected by inkjet printing head(s) other than the inkjet printing headsused for dispensing the modeling material formulation(s).

In some embodiments, exposing the building material to a condition thatinduces curing includes one or more conditions that affect curing of asupport material formulation, to thereby obtain a cured supportmaterial.

In some of any of the embodiments described herein, once a buildingmaterial is cured, the method further comprises removing the curedsupport material. Any of the methods usable for removing a supportmaterial formulation can be used, depending on the materials employed inthe modeling material formulation and the support material formulation.Such methods include, for example, mechanical removal of the curedsupport material and/or chemical removal of the cured support materialby contacting the cured support material with a solution in which it isdissolvable (e.g., an alkaline aqueous solution).

As used herein, the term “curing” describes a process in which aformulation is hardened. This term encompasses polymerization ofmonomer(s) and/or oligomer(s) and/or cross-linking of polymeric chains(either of a polymer present before curing or of a polymeric materialformed in a polymerization of the monomers or oligomers). The product ofa curing reaction is therefore typically a polymeric material and insome cases a cross-linked polymeric material. This term, as used herein,encompasses also partial curing, for example, curing of at least 20% orat least 30% or at least 40% or at least 50% or at least 60% or at least70% of the formulation, as well as 100% of the formulation.

Herein, the phrase “a condition that affects curing” or “a condition forinducing curing”, which is also referred to herein interchangeably as“curing condition” or “curing inducing condition” describes a conditionwhich, when applied to a formulation that contains a curable material,induces polymerization of monomer(s) and/or oligomer(s) and/orcross-linking of polymeric chains. Such a condition can include, forexample, application of a curing energy, as described hereinafter to thecurable material(s), and/or contacting the curable material(s) (e.g., aROMP monomer) with chemically reactive components such as othercomponents of a ROMP catalyst system (e.g., catalysts, co-catalysts,and/or activators, as described in further detail hereinbelow).

When a condition that induces curing comprises application of a curingenergy, the phrase “exposing to a condition that affects curing” meansthat the dispensed layers are exposed to the curing energy and theexposure is typically performed by applying a curing energy to thedispensed layers.

A “curing energy” typically includes application of radiation orapplication of heat.

The radiation can be electromagnetic radiation (e.g., ultraviolet orvisible light), or electron beam radiation, or ultrasound radiation ormicrowave radiation, as also described hereinabove, depending on thematerials to be cured. The application of radiation (or irradiation) iseffected by a suitable radiation source. For example, an ultraviolet orvisible or infrared or Xenon lamp can be employed, as described herein.

A curable material or system that undergoes curing upon exposure toradiation is referred to herein interchangeably as “photopolymerizable”or “photoactivatable” or “photocurable”.

When the curing energy comprises heat, the curing is also referred toherein and in the art as “thermal curing” and comprises application ofthermal energy. Applying thermal energy can be effected, for example, byheating a receiving medium onto which the layers are dispensed or achamber hosting the receiving medium, as described herein. In someembodiments, the heating is effected using a resistive heater.

In some embodiments, the heating is effected by irradiating thedispensed layers by heat-inducing radiation. Such irradiation can beeffected, for example, by means of an IR lamp or Xenon lamp, operated toemit radiation onto the deposited layer.

In some embodiments, heating is effected by infrared radiation appliedby a ceramic lamp, for example, a ceramic lamp that produces infraredradiation of from about 3 μm to about 4 μm, e.g., about 3.5 μm.

In some embodiments, the heat-inducing radiation is selected to emitradiation at a wavelength that results in efficient absorption of theheat energy by a selected ROMP monomer or mixture of monomers, so as toeffect efficient application of heat energy (efficient heating orthermal curing).

A curable material or system that undergoes curing upon exposure to heatis referred to herein as “thermally-curable” or “thermally-activatable”or “thermally-polymerizable”.

In some of any of the embodiments described herein, the method furthercomprises exposing the cured modeling material formulation(s) eitherbefore or after removal of a support material formulation, if such hasbeen included in the building material, to a post-treatment condition.The post-treatment condition is typically aimed at further hardening thecured modeling formulation(s) and/or at preventing its oxidation. Insome embodiments, the post-treatment hardens a partially-curedformulation to thereby obtain a completely cured formulation.

In some embodiments, the post-treatment is effected by exposure to heator radiation, preferably at a reduced pressure (e.g., vacuum), andoptionally at atmospheric pressure under inert atmosphere, as describedin any of the respective embodiments herein. In some embodiments, whenthe condition is heat, the post-treatment can be effected for a timeperiod that ranges from a few minutes (e.g., 10 minutes) to a few hours(e.g., 1-24 hours). In some embodiments, when the condition is heat, thepost-curing treatment can be effected for a time period that ranges froma few minutes (e.g., 10 minutes) to a few hours (e.g., 1-24 hours). Insome embodiments, the post-curing treatment is effected for 2 hours. Insome embodiments, the post-curing treatment comprises heat, and heatingis effected at a temperature that ranges from about 50° C. to about 250°C., or from about 50° C. to about 200° C., or from about 100° C. toabout 200° C., or, for example, at 150° C., and at a reduced pressure.

An inert atmosphere can be, for example, nitrogen and/or argonatmosphere.

Reduced pressure can be, for example, lower than 200 mmHg, lower than100 mmHg, or lower than 50 mmHg, for example, about 20 mmHg, althoughany other value is contemplated.

Alternatively, or in addition, the post-curing treatment comprisesapplying to a surface of (or coating) the model object, or to a part ofthe surface, a material or a composition that features anti-oxidationactivity, to thereby reduce or prevent oxidation of the model object (ora part thereof) when exposed to ambient environment. In some of theseembodiments, the material or composition is such that forms a thin,preferably, but not necessarily transparent, layer on the surface of themodel object or a part thereof. Any material or composition thatfeatures anti-oxidation activity and which can be readily applied to themodel object as described herein is contemplated. An exemplary suchcomposition is an acrylic paint, that is, a formulation that forms anacrylic paint once deposited on a surface of the object.

Applying a material or composition featuring an anti-oxidation activityand exposing to heat or radiation, within a post-curing treatment asdescribed herein, when used together, can be effected sequentially orsimultaneously. For example, a formulation forming an acrylic paint canbe applied to the surface of the model object, and exposure to heatand/or radiation can be applied thereafter, to thereby effect bothformation of a layer of the acrylic paint and further hardening of thecured modeling formulation.

In some of any of the embodiments described herein, at least one of themodeling material formulations as described herein comprises a monomerthat is polymerizable by ring opening metathesis polymerization (ROMP).Such a monomer is also referred to herein interchangeably as a ROMPmonomer, a ROMP-polymerizable monomer, a ROMP curable monomer, a ROMPcomponent, a ROMP active component, and similar diversions. In someembodiments, one or more of the modeling material formulations in the(uncured) building material comprises a catalyst for initiating a ROMPreaction of the monomer, as described in further detail hereinunder.

In some of any of the embodiments described herein, the ROMP monomer isan unsaturated cyclic monomer, preferably a strained unsaturated cyclicolefin, as described in further detail hereinunder.

In some of any of the embodiments described herein, exposing themodeling material formulation to a condition that induces curingcomprises exposing the dispensed modeling material formulation(s) to acondition for inducing initiation of ROMP of the monomer by thecatalyst, as described in further detail hereinunder. Any of theconditions for effecting curing as described hereinabove arecontemplated, depending on the materials selected for the ROMP system.

Herein throughout, a condition for inducing initiation of ROMP of themonomer by the catalyst is also referred to herein interchangeably as “aROMP inducing condition” or simply as “inducing condition”, anddescribes a condition to which a modeling material formulation isexposed so as to effect ROMP of the ROMP monomer (e.g., to effectinitiation of ROMP of the ROMP monomer by the catalyst).

It is to be noted that a building material, including the one or moremodeling material formulations included therein, can be exposed also toa condition that affects curing via other modes of action (e.g., viaother polymerization reactions and/or via cross-linking of polymericchains), that is, a non-ROMP curing condition, as described in furtherdetail hereinafter.

The ROMP inducing condition and a non-ROMP curing condition can be thesame or different.

A ROMP System:

Herein, a “ROMP system” describes a set of materials and optionallyconditions for effecting polymerization, via a ROMP reaction, of anunsaturated cyclic ROMP monomer (or a mixture of ROMP monomers). Thematerials included in a ROMP system are also referred to herein as “ROMPcomponents” or “ROMP active components”.

A ROMP system requires at least a ROMP monomer and a catalyst forinitiating the ROMP reaction. The catalyst is also referred to hereinthroughout as a “ROMP catalyst” or a “ROMP catalyst system”.

In some embodiments, a ROMP system consists of a catalyst and a ROMPmonomer. In such cases, the catalyst in referred to herein as an “activecatalyst”, which is active towards initiation of ROMP of the monomerimmediately once it contacts the monomer, without a need to apply anexternal stimulus such as, for example, heat, radiation, or chemicaladditives.

In some of these embodiments, a condition for inducing initiating ofROMP of the monomer by the catalyst requires contacting the catalystwith the ROMP monomer.

By “active towards initiation of ROMP” of the monomer it is meant thatin the presence of the catalyst, at least 50% or at least 60% or atleast 70% or at least 80% of the monomer polymerizes via ROMP mechanismto provide a respective polymer.

In some embodiments, a ROMP system consists of a catalyst and a ROMPmonomer and a condition for activating the catalyst towards initiationof ROMP of the monomer. In such cases, the catalyst is referred toherein as a “latent catalyst”, which is activatable upon exposure to thecondition. According to some of these embodiments, the catalyst isinactive towards initiation of ROMP of the monomer when the ROMP systemis not exposed to the condition that activates the catalyst, namely,prior to exposure to a ROMP inducing condition.

By “inactive towards initiation of ROMP” of the monomer it is meant thatin the presence of the catalyst, no more than 40% or no more than 30% orno more than 20% or no more than 10% or no more than 5% of the monomerpolymerizes via ROMP mechanism to provide a respective polymer.

Latent catalysts as described herein can be thermally-activatablecatalysts, which are converted into active catalysts upon exposure toheat (that is, a condition for inducing initiation of ROMP comprisesheat or heating a ROMP system, optionally in addition to contacting thecatalyst and the ROMP monomer).

Latent catalysts as described herein can be photo-activatable catalysts,which are converted into active catalysts upon exposure to radiation(that is, a condition for inducing initiation of ROMP comprises exposureto radiation or application of radiation to the ROMP system, optionallyin addition to contacting the catalyst and a ROMP monomer). Theradiation can be, for example, an electromagnetic radiation (e.g., UV orvisible or IR light), or ultrasound radiation, or heat-inducingradiation, and can be applied by a suitable source of the radiation, asdescribed herein.

Latent catalysts activatable by exposure to other conditions are alsocontemplated.

In some embodiments, a ROMP system consists of a ROMP monomer, a ROMPcatalyst and an activator, for chemically activating the ROMP catalyst.In such cases, the ROMP catalyst is inactive towards initiation of ROMPof the monomer, as defined herein, in the absence of the activator (whenit is not contacted with the activator). A ROMP catalyst that isactivatable in the presence of an activator is referred to herein alsoas a “pre-catalyst”, and the activator is referred to herein as a“co-catalyst”. A combination of pre-catalyst and an activator is alsoreferred to herein and in the art as a catalyst system, and herein alsoas a ROMP catalyst system.

By “chemically activating” it is meant that the activation of a catalystis made by an addition of a chemical entity (a chemical additive), e.g.,a chemical compound or a chemical species such as an ion.

According to some of these embodiments, the catalyst is inactive towardsinitiation of ROMP of the monomer, as defined herein, in the absence ofa respective activator.

According to these embodiments, a condition for initiating ROMP of amonomer requires a contact between the catalyst and the activator andthe catalyst and the ROMP monomer.

In some of these embodiments, the activator is an activatable activator,which is rendered active towards chemically activating the catalyst whenexposed to a certain condition. In such cases, the activator isincapable of chemically activating the catalyst unless it is activated(by exposure to the condition). Such activators are also referred toherein as “latent activators”.

A latent activator is incapable of activating a catalyst for initiatingROMP of the monomer, and can be converted to an active activator whenexposed to an activating condition (which can be the ROMP inducingcondition as described herein).

According to some of these embodiments, the activator is inactivetowards chemically activating the catalyst, and the catalyst istherefore inactive towards initiation of ROMP of the monomer when theROMP system is not exposed to the condition that activates theactivator.

By “inactive towards chemically activating the catalyst” it is meantthat no chemical reaction between the activator and the catalyst occurs,such that in the ROMP system containing the ROMP monomer, a ROMPcatalyst which is chemically activatable by the activator, and thelatent activator, no more than 40% or no more than 30% or no more than20% or no more than 10% or no more than 5% of the monomer polymerizesvia ROMP mechanism to provide a respective polymer.

Latent activators as described herein can be thermally-activatableactivators, which are converted into active activators upon exposure toheat (that is, a condition for inducing initiation of ROMP comprisesheat or heating a ROMP system, optionally in addition to contacting anactivator and a catalyst and a ROMP monomer).

Latent activators as described herein can be photo-activatablecatalysts, which are converted into active activators upon exposure toradiation (that is, a condition for inducing initiation of ROMPcomprises exposure to radiation or application of radiation to the ROMPsystem, optionally in addition to contacting an activator and a catalystand a catalyst and a ROMP monomer). The radiation can be, for example,an electromagnetic radiation (e.g., UV or visible or IR light), orultrasound radiation, and can be applied by a suitable source of theradiation.

In some of any of the embodiments described herein, a ROMP system canfurther comprise a ROMP inhibitor.

A “ROMP inhibitor” as used herein refers to a material that slows down aROMP reaction initiated by a catalyst. ROMP inhibitors can be used withactive catalysts, latent catalysts and pre-catalysts, as describedherein. In some embodiments, a ROMP inhibitor inhibits a ROMP reactioninitiated in the presence of an active catalyst, or once a latentcatalyst or pre-catalyst is converted to an active catalyst, byinterfering with the chemical reactions that activate a latent catalystor a pre-catalyst.

It is to be noted that a ROMP system as described herein refers to theactive components and/or conditions that together lead to ROMPpolymerization of a ROMP monomer. A formulation that comprises a ROMPsystem can further comprise other components which can participate inpolymerization or curing reactions (e.g., curable materials and/orsystems), and/or form a part of the final polymeric material, asdescribed in further detail hereinbelow.

Herein throughout, whenever a ROMP monomer is indicated, it is to beunderstood as encompassing one or more (e.g., a mixture of two, three ormore) ROMP monomer(s); whenever a ROMP catalyst or pre-catalyst isindicated, it is to be understood as encompassing one or more (e.g., amixture of two, three or more) catalyst(s) or pre-catalyst(s); whenevera ROMP activator is indicated, it is to be understood as encompassingone or more (e.g., a mixture of two, three or more) ROMP activator(s);whenever a ROMP inhibitor is indicated, it is to be understood asencompassing one or more (e.g., a mixture of two, three or more) ROMPinhibitor(s). Whenever a toughening agent or an impact modifying agentis indicated, it is to be understood as encompassing one or more (e.g.,a mixture of two, three, or more) agent(s). Similarly, wheneverreference to any other agent or moiety is made herein throughout, it isto be understood as encompassing one or more (e.g., a mixture of two,three or more) agent(s) or moiety/moieties.

ROMP Monomers:

A ROMP monomer as described herein describes any material that undergoesROMP in the presence of a ROMP catalyst or ROMP catalyst system.

Typically, ROMP monomers are unsaturated cyclic compounds (cyclicolefins), and preferably strained unsaturated cyclic compounds (strainedcyclic olefins).

Any compound that can undergo ROMP is encompassed by the presentembodiments.

The phrase “ROMP monomer” as used herein encompasses one ROMP monomer ora combination of ROMP monomers, and also encompasses a mixture of a ROMPmonomer with another cyclic olefin that can react with a ROMP monomerduring ROMP of the ROMP monomer, if included in the same reactionmixture. Such cyclic olefins can be recognized by those skilled in theart.

Exemplary ROMP monomers include, but are not limited todicyclopentadiene (DCPD), cyclopentadiene trimer, tetramer, pentamer,etc., norbornene, cyclooctene, cyclooctadiene, cyclobutene, cyclopropeneand substituted derivatives thereof, for example, substitutednorbornenes such as carboxylated norbornenes, butyl norbornene, hexylnorbornene, octyl norbornene.

Some exemplary ROMP monomers are presented also in Tables 1, 3, 4, 5 and7-9.

Any cyclic olefin (unsaturated cyclic compounds) suitable for themetathesis reactions disclosed herein may be used.

Herein, the phrases “cyclic olefin” and “unsaturated cyclic compound”are used interchangeably encompasses compounds comprising one, two,three or more non-aromatic rings (fused and/or unfused rings) whichcomprise at least one pair of adjacent carbon atoms in the ring whichare bound to one another by an unsaturated bond. The ring may optionallybe substituted or unsubstituted, and the cyclic olefin may optionallycomprise one unsaturated bond (“monounsaturated”), two unsaturated bonds(“di-unsaturated”), three unsaturated bond (“tri-unsaturated”), or morethan three unsaturated bonds. When substituted, any number ofsubstituents may be present (optionally from 1 to 5, and optionally 2,3, 4 or 5 substituents), and the substituent(s) may optionally be anysubstituent describes herein as being optionally attached to an alkyl oralkenyl.

Examples of cyclic olefins include, without limitation, cyclooctene,cyclododecene, and (c,t,t)-1,5,9-cyclododecatriene.

Examples of cyclic olefins with more than one ring include, withoutlimitation, norbornene, dicyclopentadiene, tricyclopentadiene, and5-ethylidene-2-norbornene.

The cyclic olefin may be a strained or unstrained cyclic olefin,provided the cyclic olefin is able to participate in a ROMP reactioneither individually or as part of a ROMP cyclic olefin composition.While certain unstrained cyclic olefins such as cyclohexene aregenerally understood to not undergo ROMP reactions by themselves, underappropriate circumstances, such unstrained cyclic olefins maynonetheless be ROMP active. For example, when present as a co-monomer ina ROMP composition, unstrained cyclic olefins may be ROMP active.Accordingly, as used herein and as would be appreciated by the skilledartisan, the term “unstrained cyclic olefin” is intended to refer tothose unstrained cyclic olefins that may undergo a ROMP reaction underany conditions, or in any ROMP composition, provided the unstrainedcyclic olefin is ROMP active.

In some embodiments of any one of the embodiments described herein, thesubstituted or unsubstituted cyclic olefin comprises from 5 to 24 carbonatoms. In some such embodiments, the cyclic olefin is a hydrocarbondevoid of heteroatoms. In alternative embodiments, the cyclic olefincomprises one or more (e.g., from 2 to 12) heteroatoms such as O, N, S,or P, for example, crown ether cyclic olefins which include numerous Oheteroatoms throughout the cycle, are within the scope of the invention.

In some embodiments of any one of the embodiments described hereinrelating to a cyclic olefin comprising from 5 to 24 carbon atoms, thecyclic olefin is monounsaturated, di-unsaturated, or tri-unsaturated.

In some embodiments of any of the embodiments described herein, thecyclic olefin has the general formula (A):

wherein:

R^(A1) and R^(A2) are each independently hydrogen, alkyl, cycloalkyl,alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, halo, hydroxy,alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, sulfinyl,sulfonyl, sulfonate, nitrile, nitro, azide, phosphonyl, phosphinyl, oxo,carbonyl, thiocarbonyl, urea, thiourea, carbamyl, N-carbamyl,O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, C-carboxy, O-carboxy,sulfonamido, and amino;

J is a saturated or unsaturated hydrocarbon, which may be substituted orunsubstituted, and may optionally comprise one or more heteroatomsbetween the carbon atoms thereof. Additionally, two or more substituentsattached to ring atoms within J may optionally be linked to form abicyclic or polycyclic olefin.

In some embodiments of any of the respective embodiments describedherein, the compound of formula (A) contains from 5 to 14 ring atoms,optionally from 5 to 8 ring atoms, for a monocyclic olefin; and, forbicyclic and polycyclic olefins, from 4 to 8 ring atoms in each ring,optionally from 5 to 7 ring atoms in each ring.

In some embodiments of any of the embodiments described herein, thecyclic olefin has the general formula (B):

wherein:

b is an integer in a range of 1 to 10, optionally 1 to 5;

R^(A1) and R^(A2) are as defined above for formula (A); and

R^(B1), R^(B2), R^(B3), R^(B4), R^(B5), and R^(B6) are eachindependently hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl,heteroaryl, heteroalicyclic, halo, hydroxy, alkoxy, aryloxy,thiohydroxy, thioalkoxy, thioaryloxy, sulfinyl, sulfonyl, sulfonate,nitrile, nitro, azide, phosphonyl, phosphinyl, oxo, carbonyl,thiocarbonyl, urea, thiourea, carbamyl, N-carbamyl, O-thiocarbamyl,N-thiocarbamyl, C-amido, N-amido, C-carboxy, O-carboxy, sulfonamido, andamino, or alternatively, any of the R^(B1), R^(B2), R^(B3), R^(B4),R^(B5), and R^(B6) moieties can be linked to any of the other R^(B1),R^(B2), R^(B3), R^(B4), B⁵, and R^(B6) moieties to provide a substitutedor unsubstituted 4- to 7-membered ring.

In some embodiments of any of the embodiments described herein, thecyclic olefin is monocyclic.

In some embodiments of any of the embodiments described herein, thecyclic olefin is monounsaturated, optionally being both monocyclic andmonounsaturated.

Examples of monounsaturated, monocyclic olefins encompassed by formula(B) include, without limitation, cyclopentene, cyclohexene,cycloheptene, cyclooctene, cyclononene, cyclodecene, cycloundecene,cyclododecene, tricyclodecene, tetracyclodecene, octacyclodecene, andcycloeicosene, and substituted versions thereof such asmethylcyclopentene (e.g., 1-methylcyclopentene, 4-methylcyclopentene),ethylcyclopentene (e.g., 1-ethylcyclopentene), isopropylcyclohexene(e.g., 1-isopropylcyclohexene), chloropentene (e.g., 1-chloropentene),fluorocyclopentene (e.g., 1-fluorocyclopentene), methoxycyclopentene(e.g., 4-methoxy-cyclopentene), ethoxycyclopentene (e.g.,4-ethoxy-cyclopentene), cyclopentene-thiol (e.g.,cyclopent-3-ene-thiol), methylsulfanyl-cyclopentene (e.g.,4-methylsulfanyl-cyclopentene), methylcyclohexene (e.g.,3-methylcyclohexene), methylcyclooctene (e.g., 1-methylcyclooctene), anddimethylcyclooctene (e.g., 1,5-dimethylcyclooctene).

In some embodiments of any of the embodiments described herein, thecyclic olefin is diunsaturated, optionally being both monocyclic anddiunsaturated.

In some embodiments, the cyclic olefin has the general formula (C):

wherein:

c and d are each independently integers in the range of from 1 to 8,optionally from 2 to 4, and optionally 2 (such that the cyclic olefin isa cyclooctadiene);

R^(A1) and R^(A2) are as defined above for formula (A); and R^(C1),R^(C2), R^(C3), R⁰⁴, R^(C5), and R^(C6) are each independently definedas for R^(B1)-R^(B6).

In some embodiments, R^(C3) and R^(C4) are substituents (i.e., nothydrogen), in which case at least one of the olefinic moieties istetrasubstituted.

Examples of diunsaturated, monocyclic olefins include, withoutlimitation, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1,4-cyclohexadiene,heptadiene (e.g., 1,3-cycloheptadiene), octadiene (e.g.,1,5-cyclooctadiene, 1,3-cyclooctadiene), and substituted versionsthereof (e.g., 5-ethyl-1,3-cyclohexadiene).

In some embodiments of any of the embodiments described herein, thecyclic olefin comprises more than two (optionally three) unsaturatedbonds. In some embodiments, such compounds are analogous to the dienestructure of formula (C), comprising at least one methylene linkage(analogous to the number of methylene linkages indicated by thevariables c and d in formula (C)) between any two olefinic segments.

In some embodiments of any of the embodiments described herein, thecyclic olefin is polycyclic.

Herein, the term “polycyclic” refers to a structure comprising two ormore fused rings.

In some embodiments of any of the embodiments described herein, thecyclic olefin is a polycyclic olefin having the general formula (D):

wherein:

R^(A1) and R^(A2) are each independently as defined above for formula(A);

R^(D1), R^(D2), R^(D3) and R^(D4) are each independently as defined forR^(B1)-R^(B6);

e is an integer in the range of from 1 to 8, optionally from 2 to 4;

f is 1 or 2; and

T is a substituted or unsubstituted saturated or unsaturated hydrocarbonof 1-4 carbon atoms in length (optionally 1 or 2 carbon atoms in length,for example, substituted or unsubstituted methyl or ethyl), O, S,N(R^(G1)), P(R^(G1)), P(═O)(R^(G1)), Si(R^(G1))₂, B(R^(G1)), orAs(R^(G1)), wherein R^(G1) is alkyl, alkenyl, alkynyl, cycloalkyl,heteroalicyclic, aryl, heteroaryl, alkoxy or aryloxy.

Cyclic olefins encompassed by formula (D) are examples of compounds inthe norbornene family.

As used herein, the term “norbornene” refers to any compound thatincludes at least one substituted or unsubstitutedbicyclo[2.2.1]hept-2-ene moiety or dehydrogenated derivative thereof,including without limitation, bicyclo[2.2.1]hept ene (referred to in theart as “norbornene”) and substituted versions thereof, norbornadiene,(bicyclo[2.2.1]hepta-2,5-diene) and substituted versions thereof, andpolycyclic norbornenes, and substituted versions thereof.

In some embodiments, the cyclic olefin is a polycyclic norbornene havingthe general formula (E):

wherein:

R^(A1) and R^(A2) are each independently as defined above for formula(A);

T is as defined above for formula (D);

R^(E1), R^(E2), R^(E3), R^(E4), R^(E5), R^(E6), R^(E7), and R^(E8) areeach independently as defined for R^(B1)-R^(B6); and

“a” represents a saturated bond or unsaturated double bond, wherein when“a” is an unsaturated double bond, one of R^(E5), R^(E6) and one ofR^(E7), R^(E8) is absent;

f is 1 or 2; and

g is an integer from 0 to 5.

In some embodiments, the cyclic olefin has the general formula (F):

wherein:

R^(F1), R^(F3) and R^(F4) defined above for R^(E4), R^(E5), R^(E6),R^(E7), and R^(E8) respectively; and

a and g are as defined in formula (E) hereinabove.

Examples of bicyclic and polycyclic olefins include, without limitation,dicyclopentadiene (DCPD); trimer and higher order oligomers ofcyclopentadiene (e.g., cyclopentadiene tetramer, cyclopentadienepentamer); ethylidenenorbornene; dicyclohexadiene; norbornene;5-methyl-2-norbornene; 5-ethyl-2-norbornene; 5-isobutyl-2-norbornene;5,6-dimethyl-2-norbornene; 5-phenylnorbornene; 5-benzylnorbornene;5-acetylnorbornene; 5-methoxycarbonylnorbornene;5-ethyoxycarbonyl-1-norbornene; 5-methyl-5-methoxy-carbonylnorbornene;5-cyanonorbornene; 5,5,6-trimethyl-2-norbornene;cyclo-hexenylnorbornene; endo,exo-5,6-dimethoxynorbornene;endo,endo-5,6-dimethoxynorbornene;endo,exo-5,6-dimethoxycarbonylnorbornene;endo,endo-5,6-dimethoxycarbonylnorbornene; 2,3-dimethoxynorbornene;norbornadiene; tricycloundecene; tetracyclododecene;8-methyltetracyclododecene; 8-ethyltetracyclododecene;8-methoxycarbonyltetracyclododecene; 8-methyl-8-tetracyclododecene;8-cyanotetracyclododecene; pentacyclopentadecene; pentacyclohexadecene;and the like, and their structural isomers, stereoisomers, and mixturesthereof.

Additional examples of bicyclic and polycyclic olefins include, withoutlimitation, C₂-C₁₂-alkyl-substituted and C₂-C₁₂-alkenyl-substitutednorbornenes, for example, 5-butyl-2-norbornene, 5-hexyl-2-norbornene,5-octyl-2-norbornene, 5-decyl-2-norbornene, 5-dodecyl-2-norbornene,5-vinyl-2-norbornene, 5-ethylidene norbornene,5-isopropenyl-2-norbornene, 5-propenyl-2-norbornene, and 5-butenylnorbornene, and the like.

In some embodiments of any of the embodiments described herein, thecyclic olefin is dicyclopentadiene; tricyclopentadiene;dicyclohexadiene; norbornene; 5-methyl-2-norbornene;5-ethyl-2-norbornene; 5-isobutyl-2-norbornene; 5,6-dimethyl norbornene;5-phenylnorbornene; 5-benzylnorbornene; 5-acetylnorbornene;5-methoxycarbonylnorbornene; 5-ethoxycarbonyl-1-norbornene;5-methyl-5-methoxy-carbonylnorbornene; 5-cyanonorbornene;5,5,6-trimethyl-2-norbornene; cyclo-hexenylnorbornene; endo,exo-5,6-dimethoxynorbornene; endo,endo-5,6-dimethoxynorbornene;endo,exo-5-6-dimethoxycarbonylnorbornene;endo,endo-5,6-dimethoxycarbonylnorbornene; 2,3-dimethoxynorbornene;norbornadiene; tricycloundecene; tetracyclododecene;8-methyltetracyclododecene; 8-ethyltetracyclododecene;8-methoxycarbonyltetracyclododecene; 8-methyl-8-tetracyclododecene;8-cyanotetracyclododecene; pentacyclopentadecene; pentacyclohexadecene;an oligomer of cyclopentadiene (e.g., cyclopentadiene tetramer,cyclopentadiene pentamer); and/or a C₂-C₁₂-alkyl-substituted norborneneor C₂-C₁₂-alkenyl-substituted norbornene (e.g., 5-butyl-2-norbornene;5-hexyl-2-norbornene; 5-octyl-2-norbornene; 5-decyl-2-norbornene;5-dodecyl-2-norbornene; 5-vinyl-2-norbornene; 5-ethylidene-2-norbornene;5-isopropenyl-2-norbornene; 5-propenyl-2-norbornene;5-butenyl-2-norbornene).

In some embodiments of any of the embodiments described herein, thecyclic olefin is dicyclopentadiene, tricyclopentadiene, or higher orderoligomer of cyclopentadiene (e.g., cyclopentadiene tetramer,cyclopentadiene pentamer), tetracyclododecene, norbornene, and/or aC₂-C₁₂-alkyl-substituted norbornene or C₂-C₁₂-alkenyl-substitutednorbornene (e.g., according to any of the respective embodimentsdescribed herein).

Additional examples for ROMP capable cyclic olefin monomers which may beoptionally used in embodiments of the invention include any polycycliccompounds which are characterized by the presence of at least twonorbornene moieties in its structure, for example:

and/or

In some embodiments of any of the embodiments described herein, thecyclic olefin is characterized by the presence of at least three rings.

In some embodiments of any of the embodiments described herein relatingto a norbornene-based monomer, a monocyclic olefin (e.g., cyclobutene,cyclopentene, cyclopentadiene, cyclooctene, cyclododecene) iscopolymerized with the norbornene-based monomer.

Without being bound by any particular theory, it is believed thatpolycyclic monomers with a rigid backbone, such as cyclopentadienetrimer (TCPD or CPD trimer) will typically produce a cross-linkedpolymer with very high Tg and heat deflection temperature (HDT), butwill also be more brittle and may have lower Impact resistance.

In some embodiments of any of the embodiments described herein, apolycyclic monomer with a rigid backbone (e.g., according to any of therespective embodiments described herein) is formulated with one or moresofter additional monomers and/or cross linkers.

Examples of additional monomers include, without limitation, monomershaving the formula:

wherein Rx and Ry are each independently hydrogen, C₁-C₂₀-alkyl,cycloalkyl, heteroalicyclic, aryl, polyethylene glycol, polypropyleneglycol or benzyl.

Example of bifunctional cyclic olefins, which may also act as crosslinkers include, without limitation, compounds having any one of thefollowing formulas:

wherein Rx and Ry are each independently hydrogen, C₁-C₂₀-alkyl,cycloalkyl, heteroalicyclic, aryl, polyethylene glycol, polypropyleneglycol or benzyl; and

K₁ and K₂ are each independently C₁-C₂₀-alkylene, cycloalkyl,heteroalicyclic, aryl, polyethylene glycol, polypropylene glycol orbenzyl.

Additional examples of bifunctional cyclic olefins include, withoutlimitation:

and

The connection between an additional monomer and/or bifunctional monomer(cross-linker) to a polycyclic (e.g., norbornene) monomer may optionallybe, without limitation, through a saturated or unsaturated carbon-carbonbond, an ester bond, and ether bond, an amine, or an amide bond.

Synthesis of norbornene derivatives described herein according to any ofthe respective embodiments may optionally be performed by Diels-Alderreaction of double bond with cyclopentadiene (CPD), as depicted inScheme 1 below:

Substituents of a polymerized cyclic olefin may optionally be in aprotected form in the monomer. For example, hydroxy groups, which mayinterfere with metathesis catalysis, may be protected by being in a formof any suitable protected group used in the art. Acceptable protectinggroups may be found, for example, in Greene et al., Protective Groups inOrganic Synthesis, 3rd Ed. (New York: Wiley, 1999).

Table A below presents non-limiting examples of suitable ROMPpolymerizable monomers according to some embodiments of the presentinvention.

TABLE A Tradename Structure Supplier DCPD Dicyclopentadiene Telene SASRIM monomer Cyclopentadiene trimer in Telene SAS dicyclopentadieneCyclopentadiene trimer Cyclopentadiene trimer Zeon CycloocteneCyclooctene Sigma Aldrich Cyclooctadiene Cyclooctadiene Sigma AldrichNorbornene Norbornene Sigma Aldrich ENB 5-Ethylidene-2-norbornene SigmaAldrich cyclododecatriene cyclododecatriene BASF

In a preferred embodiment, the ROMP monomer is or comprises DCPD due toits high reactivity, and the high thermal resistance and toughnessproperties exhibited by a printed object made therefrom.

In a preferred embodiment, the ROMP monomer is or comprises a CPD trimerdue to its suitable viscosity and the high thermal resistance exhibitedby a printed object made therefrom.

In a preferred embodiment, a ROMP monomer is or comprises a mixture ofDCPD and CPD trimer, for example, a mixture known in the art, and alsoreferred to herein as “RIM monomer”. In some embodiments, such a mixturecomprises DCPD at a concentration ranging from about 70% to about 99%,or from 85% to about 95%, by weight, of the total weight of a ROMPmonomer, and a CPD trimer at a concentration ranging from about 30% toabout 1%, or from about 15% to about 5%, respectively, by weight, of thetotal weight of a ROMP monomer.

In a commercially available “RIM monomer”, a concentration of DCPD istypically from about 90% to about 92%.

In some embodiments, a ROMP monomer is or comprises about 91% DCPD andabout 9% CPD trimer, as described herein.

ROMP Catalysts and Catalyst Systems:

ROMP catalysts typically include metal carbene organometallic complexes,with the metal being typically, but not necessarily, a transition metalsuch as ruthenium, molybdenum, osmium or tungsten.

Ruthenium based ROMP catalysts are more stable on exposure to noncarbon-carbon double-bond functional groups, and to other impuritieslike water and oxygen. These catalysts can typically be used in lowloading in the formulation (e.g., in a range of from about 0.002% toabout 0.05% by weight of the total weight of a modeling materialformulation containing same).

Ruthenium based ROMP catalysts that are usable in the context ofembodiments of the present invention are marketed, for example, byMateria, Umicore, Evonic and BASF.

Exemplary ruthenium-based ROMP catalysts include, Grubbs 1^(st) and2^(nd) generation catalysts, Hoveyda-Grubbs catalysts, umicore 41,umicore 42, umicore 61SIMes, and catMETium RF1.

ROMP catalysts can be divided into active catalysts, latent catalystsand pre-catalysts.

An active catalyst is a ROMP catalyst that initiates ROMP of a monomerwhen in contact with the ROMP monomer, without requiring a stimulus.ROMP active catalysts are typically active at room temperature.

Exemplary active catalysts usable in the context of the presentembodiments are the Grubbs 2^(nd) generation, Hoveyda-Grubbs 2^(nd)generation, and Grubbs 3^(nd) generation catalysts, which are realizedby any person skilled in the art.

Active catalysts are suitable for use in the context of the presentembodiments in dual- or multi-jetting methodologies. Active catalystsare suitable for use in the context of the present embodiments insingle-jetting methodologies, when physically separated from the ROMPmonomer, and optionally other components in the modeling materialformulation.

A latent catalyst is a ROMP catalyst that initiates ROMP of a monomerwhen in contact with the ROMP monomer, upon exposure to a physicalstimulus, typically heat or radiation, as described herein. A latentcatalyst is inactive in initiating ROMP of a monomer in the absence of asuitable physical stimulus.

A latent catalyst typically includes a chelating (e.g., donor) ligandwhich “blocks” a coordinative site of the metal and thus renders thecatalyst inactive. Activating the catalyst is effected by dissociatingthe chelating ligand from the metal center, to thereby render it activetowards metathesis.

In a latent catalyst, dissociating the chelating ligand requires aphysical external stimulus, as described herein. The type of theexternal stimulus is determined by the nature of the metal, thechelating ligand and other ligands in the transition metal complex.

Latent ROMP catalysts that are activated in response to heat are alsoreferred to as thermally-activatable catalysts. These include, forexample, S-chelated ruthenium catalysts such as described, for example,in Diesendruck, C. E.; Vidaysky, Y.; Ben-Asuly, A.; Lemcoff, N. G., J.Polym. Sci., Part A: Polym. Chem. 2009, 47, 4209-4213, which isincorporated by reference as if fully set forth herein.

An exemplary S-chelated thermally-activatable latent catalyst is:

Other exemplary thermally-activatable ROMP catalysts include N-chelatedruthenium catalysts, such as, for example, described in Szadkowska etal., Organometallics 2010, 29, 117-124, which is incorporated byreference as if fully set forth herein.

Exemplary N-chelated thermally-activatable latent catalyst include,without limitation:

Any other thermally-activatable ROMP catalysts are contemplated.

Latent ROMP catalysts that are activated in response to radiation arealso referred to as photoactivatable catalysts.

Photoactivatable ROMP catalysts are mostly UV-activatable catalysts, inwhich dissociation of a chelating ligand is effected in the presence ofUV radiation. Exemplary UV-activatable ROMP latent catalysts aredescribed, for example, in Vidaysky, Y. and Lemcoff, N. G. Beilstein J.Org. Chem., 2010, 6, 1106-1119; Ben-Asuly et al., Organometallics, 2009,28, 4652-4655; Diesendruck et al., J. Polym. Sci., Part A: Polym. Chem.2009, 47, 4209-4213; Wang et al., Angew. Chem. Int. Ed. 2008, 47,3267-3270; and U.S. Patent Application Publication No. 2009-0156766, allof which are incorporated by reference as if fully set forth herein.

UV-activatable ROMP catalysts can be, for example, 0-chelated andS-chelated Ruthenium catalysts.

Non-limiting examples include the following:

with R being Ph, beta-Naph, 1-Pyrenyl, or i-Pr;

and all catalysts described in Vidaysky, Y. and Lemcoff, N. G. BeilsteinJ. Org. Chem., 2010, 6, 1106-1119.

UV-activatable ROMP catalysts can be, for example, tungsten catalystssuch as, for example:

Photoactivatable latent catalyst can also be activated in response toultrasound radiation. Such catalysts are described, for example, inPiermattei et al., Nature Chemistry, DOI: 10.1038/NCHEM.167, which isincorporated by reference as if fully set forth herein.

Latent catalysts as described herein are usable in the context of any ofthe embodiments described herein, including single jetting methodologiesand multi jetting methodologies.

A ROMP pre-catalyst is a ROMP catalyst that initiates ROMP of a monomerwhen in contact with the ROMP monomer, upon exposure to a chemicalstimulus, as described herein, typically an addition of an acid or aproton, which converts the pre-catalyst to an active catalyst (whichinduces ROMP of a ROMP monomer when in contact with the ROMP monomer). Apre-catalyst is inactive in initiating ROMP of a monomer in the absenceof the chemical stimulus.

A pre-catalyst, similarly to a latent catalyst, typically includes achelating (e.g., donor) ligand which “blocks” a coordinative site of themetal and thus renders the catalyst inactive. Activating the catalyst iseffected by dissociating the chelating ligand from the metal center, tothereby render it active towards metathesis.

In a pre-catalyst, dissociating the chelating ligand requires a chemicalstimulus, typically a presence of an acid. The agent that exerts achemical stimulus that activates the catalyst is referred to herein asan activator or a co-catalyst.

A ROMP pre-catalyst and a suitable activator form together a catalystsystem.

The activator can be, for example, an acid, such as HCl, an acidgenerator such as, but not limited to, (R_(n)SiCl_(4-n)), with R beingan alkyl or aryl, and n being 1, 2, or 3, or an acid generator asdescribed, for example, in EP Patent No. 1757613 and U.S. Pat. No.8,519,069, the teachings of which are incorporated by reference as iffully set forth herein.

In some embodiments, when n is 2 or 3, one or the R groups can behydrogen, and the R groups can be the same or different, as long as atleast one of the R groups is an alkyl or aryl. Exemplary activators arepresented in Table B below.

TABLE B Tradename Structure Supplier Trichloro(phenyl)silane

Sigma Aldrich Acid activator HCl Sigma Acid Aldrich activatorChlorophenylsilane

Sigma Aldrich Acid activator Dichloro(phenyl)silane

Sigma Aldrich Acid activator Dichloromethyl(phenyl)silane

Sigma Aldrich Acid activator ChloroDimethyl Phenyl Silane

Sigma Aldrich Acid activator ChloroTrimethylSilane

TCI Acid activator Butyl(chloro)dimethyl Silane,

TCI Acid activator Chloro-decyl-dimethyl Silane

TCI Acid activator Chloro(chloromethyl)dimethyl

TCI Acid activator Chloro(dichloromethyl) dimethylsilane

Alfa Aesar Acid activator Pentafluoropropionic acid

Sigma Non chloride Acid activator Trifluoroacetic acid

Sigma Non chloride Acid activator Trichloroacetic acid

Sigma Acid activator Trichlorododecyl silane (TCSA)

Sigma- Aldrich Acid activator Trichloro(octadecyl) silaneCH₃(CH₂)₁₆CH₂SiCl₃ Sigma- Acid Aldrich activator Dichlorodiphenyl silane

Sigma- Aldrich Acid activator Perfluoro decyldimethylchloro silane

Acros Acid activator Perfluoro decylmethyl dichlorosilane

Acros Acid activator

Alternatively, the activator is activatable in response to an externalstimulus, for example, heat or radiation.

A group of latent activators which are usable in the context of thepresent embodiments is known in the art as photoacid generators (PAG).Such activators and corresponding pre-catalysts are described forexample, in Keitz, B. K.; Grubbs, R. H. J. Am. Chem. Soc. 2009, 131,2038-2039, which is incorporated by reference as if fully set forthherein.

Additional exemplary PAG include sulfonium salts such as triarylsulfonium chloride and UVI 6976, iodonium salt Uvacure 1600, Speedcure937, Irgacure 250, Irgacure PAG 103, Irgacure PAG 203,2-(4-Methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine and TMCH.Other exemplary commercially available PAG are described in Tables 1 and3 hereinunder.

Acid-activatable ROMP catalysts are described, for example, in U.S. Pat.No. 6,486,279. Other catalysts that can be activated by PAG are acidactivatable pre-catalysts such as the Schiff base-chelated catalystsdescribed in EP Patent No. 1757613 and U.S. Pat. No. 8,519,069.

Other ROMP catalyst systems are recognizable by any person skilled inthe art.

Additional exemplary ROMP catalysts and catalyst systems usable in thecontext of the present embodiments are described in Tables 1 and 3hereinbelow.

Additional exemplary ROMP catalysts usable in the context of the presentembodiments are described in WO 2014/144634, which is incorporated byreference as if fully set forth herein.

In some embodiments, a ROMP catalyst can be represented by the followingFormula:

wherein,M is a Group 8 transition metal, particularly Ru or Os, or, morepreferably, Ru (ruthenium);X¹, X², and L¹ are neutral ligands commonly used for olefin metathesiscatalyst, particularly Ru-based catalyst;Y is a heteroatom selected from N, O, S, and P; preferably Y is O or N;R⁵, R⁶, R⁷, and R⁸ are each, independently, selected from the groupconsisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, aryl,heteroalkyl, heteroatom containing alkenyl, heteroalkenyl, heteroaryl,alkoxy, alkenyloxy, aryloxy, alkoxycarbonyl, carbonyl, alkylamino,alkylthio, aminosulfonyl, monoalkylaminosulfonyl, dialkylaminosulfonyl,alkylsulfonyl, nitrile, nitro, alkylsulfinyl, trihaloalkyl,perfluoroalkyl, carboxylic acid, ketone, aldehyde, nitrate, cyano,isocyanate, hydroxyl, ester, ether, amine, imine, amide,halogen-substituted amide, trifluoroamide, sulfide, disulfide,sulfonate, carbamate, silane, siloxane, phosphine, phosphate, borate, or-A-Fn, wherein “A” and Fn have been defined above; and any combinationof Y, Z, R⁵, R⁶, R⁷, and R⁸ can be linked to form one or more cyclicgroups;n is 0, 1, or 2, such that n is 1 for the divalent heteroatoms O or S,and n is 2 for the trivalent heteroatoms N or P; andZ is a group selected from hydrogen, alkyl, aryl, functionalized alkyl,functionalized aryl where the functional group(s) may independently beone or more of the following: alkoxy, aryloxy, halogen, carboxylic acid,ketone, aldehyde, nitrate, cyano, isocyanate, hydroxyl, ester, ether,amine, imine, amide, trifluoroamide, sulfide, disulfide, carbamate,silane, siloxane, phosphine, phosphate, or borate; methyl, isopropyl,sec-butyl, t-butyl, neopentyl, benzyl, phenyl and trimethylsilyl; andwherein any combination or combinations of X¹, X², L¹, Y, Z, R⁵, R⁶, R⁷,and R⁸ may be linked to a support. Additionally, R⁵, R⁶, R⁷, R⁸, and Zmay independently be thioisocyanate, cyanato, or thiocyanato.

Additional exemplary ROMP catalysts can be represented by the followingformula:

wherein M is a Group 8 transition metal, particularly ruthenium orosmium, or more particularly, ruthenium;

X¹, X², L¹, and L² are common ligands of catalysts as defined above; and

R^(G1), R^(G2), R^(G3), R^(G4), R^(G5), and R^(G6) are eachindependently selected from the group consisting of hydrogen, halogen,alkyl, alkenyl, alkynyl, aryl, heteroalkyl, heteroatom containingalkenyl, heteroalkenyl, heteroaryl, alkoxy, alkenyloxy, aryloxy,alkoxycarbonyl, carbonyl, alkylamino, alkylthio, aminosulfonyl,monoalkylaminosulfonyl, dialkylaminosulfonyl, alkylsulfonyl, nitrile,nitro, alkylsulfinyl, trihaloalkyl, perfluoroalkyl, carboxylic acid,ketone, aldehyde, nitrate, cyano, isocyanate, thioisocyanate, cyanato,thiocyanato, hydroxyl, ester, ether, thioether, amine, alkylamine,imine, amide, halogen-substituted amide, trifluoroamide, sulfide,disulfide, sulfonate, carbamate, silane, siloxane, phosphine, phosphate,borate, or -A-Fn, wherein “A” is a divalent hydrocarbon moiety selectedfrom alkylene and arylalkylene, wherein the alkyl portion of thealkylene and arylalkylene groups can be linear or branched, saturated orunsaturated, cyclic or acyclic, and substituted or unsubstituted,wherein the aryl portion of the arylalkylene can be substituted orunsubstituted, and wherein heteroatoms and/or functional groups may bepresent in either the aryl or the alkyl portions of the alkylene andarylalkylene groups, and Fn is a functional group, or any one or more ofthe R^(G1), R^(G2), R^(G3), R^(G4), R^(G5), and R_(G6) may be linkedtogether to form a cyclic group.

Additional ROMP catalysts can be represented by the following formula:

wherein M is a Group 8 transition metal, particularly ruthenium orosmium, or more particularly, ruthenium;

X¹ and L¹ are common ligands as defined above;

Z is selected from the group consisting of oxygen, sulfur, selenium,NR^(JU), PR^(JU), AsR^(JU), and SbR^(JU); and

R^(J1), R^(J2), R^(J3), R^(J4), R^(J5), R^(J6), R_(J7), R^(J8), R^(J9),R_(J10), and R^(JU) are each independently selected from the groupconsisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, aryl,heteroalkyl, heteroatom containing alkenyl, heteroalkenyl, heteroaryl,alkoxy, alkenyloxy, aryloxy, alkoxycarbonyl, carbonyl, alkylamino,alkylthio, aminosulfonyl, monoalkylaminosulfonyl, dialkylaminosulfonyl,alkylsulfonyl, nitrile, nitro, alkylsulfinyl, trihaloalkyl,perfluoroalkyl, carboxylic acid, ketone, aldehyde, nitrate, cyano,isocyanate, thioisocyanate, cyanato, thiocyanato, hydroxyl, ester,ether, thioether, amine, alkylamine, imine, amide, halogen-substitutedamide, trifluoroamide, sulfide, disulfide, sulfonate, carbamate, silane,siloxane, phosphine, phosphate, borate, or -A-Fn, wherein “A” is adivalent hydrocarbon moiety selected from alkylene and arylalkylene,wherein the alkyl portion of the alkylene and arylalkylene groups can belinear or branched, saturated or unsaturated, cyclic or acyclic, andsubstituted or unsubstituted, wherein the aryl portion of thearylalkylene can be substituted or unsubstituted, and wherein heteroatoms and/or functional groups may be present in either the aryl or thealkyl portions of the alkylene and arylalkylene groups, and Fn is afunctional group, or any one or more of the R^(J1), R^(J2), R^(J3),R^(J4), R^(J5), R^(J6), R^(J7), R^(J8), R^(J9), R^(J1o), and R^(JU) maybe linked together to form a cyclic group.

Additional ROMP catalysts can be represented by the following formula:

wherein M is a Group 8 transition metal, particularly ruthenium orosmium, or more particularly, ruthenium;

X¹, L¹, R¹, and R² are as commonly used in ligands of ROMP catalysts;

Z is selected from the group consisting of oxygen, sulfur, selenium,NR^(K5), PR^(K5), AsR^(K5), and SbR^(K5);

m is 0, 1, or 2; and R^(k1), R^(k2), R^(k3), R^(k4), and R^(k5) are eachindependently selected from the group consisting of hydrogen, halogen,alkyl, alkenyl, alkynyl, aryl, heteroalkyl, heteroatom containingalkenyl, heteroalkenyl, heteroaryl, alkoxy, alkenyloxy, aryloxy,alkoxycarbonyl, carbonyl, alkylamino, alkylthio, aminosulfonyl,monoalkylammosulfonyl, dialkylaminosulfonyl, alkylsulfonyl, nitrile,nitro, alkylsulfinyl, trihaloalkyl, perfluoroalkyl, carboxylic acid,ketone, aldehyde, nitrate, cyano, isocyanate, thioisocyanate, cyanato,thiocyanato, hydroxyl, ester, ether, thioether, amine, alkylamine,imine, amide, halogen-substituted amide, trifluoroamide, sulfide,disulfide, sulfonate, carbamate, silane, siloxane, phosphine, phosphate,borate, or -A-Fn, wherein “A” is a divalent hydrocarbon moiety selectedfrom alkylene and arylalkylene, wherein the alkyl portion of thealkylene and arylalkylene groups can be linear or branched, saturated orunsaturated, cyclic or acyclic, and substituted or unsubstituted,wherein the aryl portion of the arylalkylene can be substituted orunsubstituted, and wherein hetero atoms and/or functional groups may bepresent in either the aryl or the alkyl portions of the alkylene andarylalkylene groups, and Fn is a functional group, or any one or more ofthe R^(K1), R^(K2), R^(K3), R^(K4), and R^(K5) may be linked together toform a cyclic group.

Additional ROMP catalysts can be represented by the following formula I:

wherein:

M is a Group 8 transition metal;

L¹ and L² are neutral electron donor ligands;

X¹ and X² are anionic ligands; and

R¹ and R² are independently selected from hydrogen, hydrocarbyl,substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substitutedheteroatom-containing hydrocarbyl, and functional groups,

wherein any two or more of X¹, X², L¹, L², R¹, and R² can be takentogether to form a cyclic group, and further wherein any one or more ofX¹, X², L¹, L², R¹, and R² may be attached to a support.

Preferred catalysts contain Ru or Os as the Group 8 transition metal,with Ru particularly preferred.

The catalysts having the structure of formula (I) are in one of twogroups. In the first group, L¹ and L² are independently selected fromphosphine, sulfonated phosphine, phosphite, phosphinite, phosphonite,arsine, stibine, ether, amine, amide, imine, sulfoxide, carboxyl,nitrosyl, pyridine, substituted pyridine, imidazole, substitutedimidazole, pyrazine, and thioether. Exemplary ligands are trisubstitutedphosphines. The first group of catalysts, accordingly, is exemplified bythe ruthenium bisphosphine complex (PCy₃)₂(Cl)₂Ru═CHPh (1):

The catalysts of the second group are transition metal carbenecomplexes, preferably ruthenium carbene complexes, wherein L² is asdefined above and L¹ is a carbene having the structure of formula (II):

such that the complex has the structure of formula (IIA)

wherein:

X¹, X², L¹, L², R¹, and R² are as defined above;

X and Y are heteroatoms selected from N, O, S, and P;

p is zero when X is O or S, and p is 1 when X is N or P;

q is zero when Y is O or S, and q is 1 when Y is N or P;

Q¹, Q², Q³, and Q⁴ are independently selected from hydrocarbylene,substituted hydrocarbylene, heteroatom-containing hydrocarbylene,substituted heteroatom-containing hydrocarbylene, and —(CO)—, andfurther wherein two or more substituents on adjacent atoms within Q maybe linked to form an additional cyclic group;

w, x, y, and z are independently zero or 1; and

R³, R^(3A), R⁴, and R^(4A) are independently selected from hydrogen,hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl,and substituted heteroatom-containing hydrocarbyl,

wherein any two or more of X¹, X², L², R¹, R², R³, R^(3A), R⁴, andR^(4A) can be taken together to form a cyclic group, and further whereinany one or more of X¹, X², L², R¹, R², R³, R^(3A), R⁴, and R^(4A) may beattached to a support.

The second group of catalysts, accordingly, is exemplified by theruthenium carbene complex (IMesH₂)(PCy₃)(Cl)₂Ru═CHPh (2):

Additional transition metal carbene complexes useful as catalysts inconjunction with the present invention include, but are not limited to,neutral ruthenium or osmium metal carbene complexes containing metalcenters that are formally in the +2 oxidation state, have an electroncount of 16, and are penta-coordinated. Other preferred metathesiscatalysts include, but are not limited to, cationic ruthenium or osmiummetal carbene complexes containing metal centers that are formally inthe +2 oxidation state, have an electron count of 14, and aretetra-coordinated. Still other preferred metathesis catalysts include,but are not limited to, neutral ruthenium or osmium metal carbenecomplexes containing metal centers that are formally in the +2 oxidationstate, have an electron count of 18, and are hexa-coordinated.

ROMP Inhibitors:

ROMP inhibitors, as described herein, are typically Lewis base compoundssuch as triphenyl phosphine (TPP), trialkylphosphite and pyridine.

Any other ROMP inhibitors are contemplated.

Exemplary ROMP Systems

Table 1 below presents a list of exemplary components which can beincluded, in any combination, in a ROMP system as described herein inany one of the embodiments and any combinations thereof. In embodimentspertaining to a dual jetting methodology, the components can be includedin one or more modeling material formulations, as described herein.

TABLE 1 Trade Name Chemical Type Function Supplier ULTRENE ™ 99Dicyclopentadiene ROMP Monomer Cymetech DCPD (bifunctional) ULTRENE ™99-X Cyclopentadiene trimer in ROMP Monomer Cymetech DCPD (X = 6-20%)dicyclopentadiene (bifunctional) Cyclopentadiene Cyclopentadiene trimerROMP Monomer Sinosteel Anshan trimer (bifunctional) Research Instituteof thermo-energy Cyclooctene Cyclooctene ROMP Monomer Sigma AldrichCyclooctadiene Cyclooctadiene ROMP Monomer Sigma Aldrich Norbornene ROMPMonomer FA-512AS Dicyclopentadienyloxyethyl Dual curing Hitachi acrylateROMP/UV chemicals monomer FA-511AS Dicyclopentadieny acrylate Dualcuring Hitachi ROMP/UV chemicals monomer Kraton no. 1102Styrene-butadiene-styrene rubber GLS rubber Polybutadiene rubber LanexssVistalon ethylene propylene diene rubber ExonMobile (EPDM) rubberchemicals Exact plastomers Rubber-plastic ExonMobile chemicals Ethanox702 4,4′-Methylenebis(2,6-di- antioxidant Albemarle tert-butylphenol)Grubbs 1^(st) generation Benzylidene- ROMP catalyst Materia catalystbis(tricyclohexylphosphine)- (active at room dichlororutheniumtemperature) Grubbs 2^(st) generation [1,3-bis-(2,4,6- ROMP catalystMateria catalysts trimethylphenyl)-2- (active at roomimidazolidinylidene] dichlor- temperature) o(phenylmethylene)(tricyclo-hexylphosphine)ruthenium Hoveyda-Grubbs 1^(st) Dichloro(o-isopropoxy-ROMP catalyst Materia Generation Catalyst phenylmethylene)(tri- (activeat room cyclohexylphosphine)ruth- temperature) enium(II) Hoveyda-Grubbs2^(nd) [1,3-Bis-(2,4,6- ROMP catalyst Materia Generation Catalysttrimethylphenyl)-2- (active at room imidazolidinylidene]dichlor-temperature) o(oisopropoxyphenylmethyl- ene)ruthenium Umicore 41[1,3-Bis(mesityl)-2- ROMP catalyst Umicore imidazolidinyl-idene]-[2-(Pre-catalyst, [[(4-methylphenyl)imin- activatable by ano]methyl]-4-nitro-phenolyl]- acid) [3-phenyl-indenylidene](chlor-o)ruthenium(II) Umicore 42 [1,3-Bis(mesityl)-2- ROMP catalyst Umicoreimidazolidinylidene]- (Pre-catalyst, [2-[[(2- activatable by anmethylphenyl)imino]methyl]- acid) phenolyl]-[3-phenyl-indenyliden](chloro)ruth- enium(II) Umicore 22 cis-[1,3-Bis(2,4,6- ROMPcatalyst Umicore trimethylphenyl)-2- (thermally-imidazolidinylidene]dichloro- activatable latent (3-phenyl-1H-inden-1-catalyst) ylidene)(triisopropylphos- phite)ruthenium(II) Umicore 21,3-Bis(2,4,6- ROMP catalyst Umicore trimethylphenyl)-2- (active at roomimidazolidinylidene]di- temperature) chloro(3-phenyl-1H-inden-1-ylidene)(tricyclohexylphos- phine)ruthenium(II) Umicore 61[1,3-Bis(2,4,6- ROMP catalyst Umicore trimethylphenyl)-2- (active atroom imidazolidinylidene]dichlor- temperature) o[2-methyl(phenyl)amin-o]benzylidene]ruthenium(II) Triphenyl phosphine Triphenyl phosphine ROMPinhibitor Sigma aidrich Triethylphosphite Triethylphosphite ROMPinhibitor Sigma aldrich Trimethylphosphite Trimethylphosphite ROMPinhibitor Sigma aldrich tributylphosphite tributylphosphite ROMPinhibitor Sigma aldrich Irgacure PAG103 PAG BASF (latent activator)Irgacure PAG121 PAG BASF (latent activator) Trichloro(phenyl)silaneTrichloro(phenyl)silane Acid generator Aldrich (activator) HCl Acid

The Modeling Material Formulations:

According to some of any of the embodiments described herein, thebuilding material comprises one or more modeling material formulationswhich, upon being dispensed, can undergo a ROMP reaction.

According to some of any of the embodiments described herein, thebuilding material comprises one or more modeling material formulationswhich form a ROMP system as described herein.

As is known in the art and discussed briefly hereinabove, ROMP reactionstypically require a catalyst for initiating the polymerization reaction.As further discussed herein, once an active catalyst contacts a ROMPmonomer, the polymerization reaction typically starts immediately,sometime without application of a curing energy, and hence modelingmaterial formulations in which an active catalyst, as described herein,is utilized “as is”, are inapplicable for 3D inkjet printing.

Embodiments of the present invention therefore relate to modelingmaterial formulations which are designed such that, prior to exposure toa suitable condition, the ROMP system is inactive, that is a ROMPcatalyst does not initiate ROMP of the monomer, and a ROMP monomer doesnot polymerize via ROMP to provide a respective polymer, as describedherein.

Embodiments of the present invention therefore relate to modelingmaterial formulations which are designed such that, prior to exposure toa suitable condition, the catalyst does not initiate the ROMP reaction,that is, prior to exposure to a suitable condition, at least 50%,preferably at least 60%, preferably at least 70%, at least 80%, at least90%, at least 95% and even 100% of the ROMP monomers do not undergopolymerization. In other words, prior to exposure of a ROMP system to asuitable condition, no more than 40% or no more than 30% or no more than20% or no more than 10% or no more than 5% of the monomer polymerizesvia ROMP mechanism to provide a respective polymer.

Such modeling material formulations are characterized by a viscosity ofno more than 35 centipoises, or no more than 25 centipoises at atemperature of the inkjet printing head during the dispensing.

In some embodiments, such modeling material formulations arecharacterized by the indicated viscosity at a temperature lower than 70°C., or lower than 65° C., or lower than 60° C., or lower than 50° C., orlower than 40° C., or lower than 30° C., and even at room temperature(e.g., 25° C.). Such a viscosity is indicative of the presence (e.g., ofmore than 80%) of non-polymerizable ROMP monomers in the formulation, orof the absence (e.g., less than 20% of the formulation) of polymericmaterials obtained by ROMP in the formulation.

The modeling material formulations described herein are thereforedesigned such that ROMP of the ROMP monomers is not effected when theformulations pass through the inkjet printing heads.

Embodiments of the present invention further relate to modeling materialformulations which are designed such that, upon exposure to a suitablecondition (an inducing condition as described herein), the ROMP systembecomes active, that is a ROMP catalyst is active towards ROMP of themonomer, and a ROMP monomer undergo polymerization via ROMP to provide arespective polymer.

Embodiments of the present invention relate to modeling materialformulations which are designed such that, upon exposure to a suitablecondition, the catalyst initiates the ROMP reaction, that is, uponexposure to a suitable condition, at least 50%, preferably at least 60%,preferably at least 70%, at least 80%, at least 90%, at least 95% andeven 100% of the ROMP monomers undergo polymerization via ROMP reaction.

In some of any of the embodiments described herein, the buildingmaterial comprises one (single) type of a modeling material formulation.Such embodiments are also referred to herein as “single jetting”methodology or approach.

In some of these embodiments, the modeling material formulationcomprises only ROMP monomers as curable materials. Such embodiments arealso referred to herein as “single jetting single curing” methodology orapproach.

In some of these embodiments, the modeling material formulationcomprises in addition to ROMP monomers, also one or more types ofmonomers which are polymerizable via a non-ROMP reaction, as curablematerials. Such embodiments are also referred to herein as “singlejetting dual curing” or “single jetting multi-curing” methodology orapproach.

In some of any of the embodiments described herein, the buildingmaterial comprises two or more types of a modeling material formulation.Such embodiments are also referred to herein as “dual jetting” or “multijetting” methodology or approach, respectively.

In some of these embodiments, each of the modeling material formulationscomprises only ROMP monomers as curable materials. Such embodiments arealso referred to herein as “dual jetting single curing” or “multijetting single curing” methodology or approach.

In some of these embodiments, the modeling material formulationscomprise in addition to ROMP monomers, also one or more types ofmonomers which are polymerizable via a non-ROMP reaction, as curablematerials. Such embodiments are also referred to herein as “multijetting multi-curing” or “dual jetting multi-curing” or “dual jettingdual curing” methodology or approach.

Generally, in the above terminology, “jetting” refers to the number ofmodeling material formulations included in the building material, and“curing” refers to the number of polymerization reactions that occurwhen the dispensed layers are exposed to a curing condition (e.g., aROMP inducing condition, or a ROMP inducing condition and one or moreadditional curing conditions).

It is to be noted that dual curing or multi curing refers herein to thetype of polymerization reactions and not to the number of conditionsapplied for inducing curing.

“Single Jetting Single Curing” Modeling Material Formulation:

According to some of any of the embodiments described herein, thebuilding material comprises a single modeling material formulation, andthe single modeling material comprises all the components of a ROMPsystem, as described herein in any of the respective embodiments.

In some of these embodiments, the ROMP system consists of a ROMP monomeras described herein and an active catalyst, as defined herein. Accordingto these embodiments, the modeling material formulation comprises a ROMPcatalyst and a ROMP monomer, and is such that the catalyst is activetowards initiating ROMP of the monomer. The ROMP system in the modelingmaterial formulation, according to these embodiments is an active ROMPsystem, in which the ROMP catalyst initiates ROMP of the monomer whenthe catalyst contacts the monomer.

According to some of these embodiments, the active catalyst and the ROMPmonomer are physically separated in the modeling material formulation,such that no contact is effected between the catalyst and the ROMPmonomer and hence the ROMP system is inactive, and the catalyst does notinitiate ROMP of the monomer, as described herein. In these embodiments,the ROMP system is inactive in the modeling material formulation due tophysical separation between the catalyst and the ROMP monomer.

According to some of these embodiments, the ROMP system becomes activeonce the physical separation is removed. Hence, in some embodiments, thecondition is removal of the physical separation between the catalyst andthe ROMP monomer. The physical separation results in a contact betweenthe catalyst and the ROMP monomer and in an active ROMP system in whichthe catalyst initiates ROMP of the monomer.

In some embodiments, exposing the modeling material formulation to acondition for inducing initiation of ROMP of the monomer by the catalystcomprises removal of a physical separation between a ROMP catalyst andthe ROMP monomer.

Physical separation can be effected, for example, by encapsulation ofone or more components of the ROMP system.

By “encapsulation” it is meant that a component is enveloped by acapsule, whereby a capsule is used herein to describe a closed structureby which a component is enveloped. In some embodiments, the capsule hasa core-shell structure in which the core is the encapsulated componentwhich is enveloped by a shell.

Herein, the terms “physically separated” and “encapsulated” or “physicalseparation” and “encapsulation” are sometimes used interchangeably, forsimplicity.

In some embodiments one of the catalyst and the ROMP monomer isencapsulated and the other is not encapsulated. In some embodiments,each of the ROMP monomer and ROMP catalyst is individually encapsulated(enveloped by a capsule). The capsules encapsulating the ROMP monomercan be the same as or different from the capsules encapsulating the ROMPcatalyst.

The capsule may have any shape and can be made of any material.

In some embodiments, the capsule is designed so as to release itscontent, namely, the encapsulated ROMP component (ROMP monomer or ROMPcatalyst) upon being exposed to a condition.

In some embodiments, exposure to a condition that induces initiation ofROMP monomer by the ROMP catalyst comprises exposure to a condition thataffects release of a ROMP component from a capsule. That is, the ROMPincluding condition is a condition that degrades a capsule and resultsin contacting the catalyst with the ROMP monomer.

In some embodiments, the release of a ROMP component from a capsule iseffected by exposure to a condition that affects degradation of thecapsule.

Degradation of the capsule can be effected, for example, mechanically,so as to affect rupture or breaking of the capsule, and the condition issuch that causes mechanical degradation of the capsule.

The mechanical degradation can be effected, for example, by applicationof mechanical forces such as shear forces.

In some embodiments, mechanical degradation is effected by exposing thecapsule to shear forces, for example, by passing a modeling materialformulation comprising the capsule through one or more inkjet printingheads (e.g., Ricoh Gen 3) which allow jetting at a frequency range offrom about 10 kHz to about 30 kHz.

Alternatively, shear forces at such a rate are applied to the dispensedlayers of the formulation (e.g., to the receiving tray).

Degradation of the capsule can be effected, for example, physically orchemically, by application of, for example, heat or radiation to thecapsule so as to decompose capsule or melt the capsule's shell.

Degradation of the capsule can thus be effected by exposing the capsuleto heat or radiation, to thereby release its content.

Non-limiting examples for encapsulation of a ROMP catalyst and/or a ROMPmonomer include utilizing capsules made of, for example, wax, degradablepolymeric materials, degradable micelles, sol-gel matrices, and/orclays. Exemplary degradable capsules are described, for example, in Adv.Funct. Mater. 2008, 18, 44-52; Adv. Mater. 2005, 17, 39-42; and Pastine,S. J.; Okawa, D.; Zettl, A.; Fréchet, J. M. J. J. Am. Chem. Soc. 2009,131, 13586-13587. doi:10.1021/ja905378v; all of which are incorporatedby reference as if fully set forth herein.

In some embodiments, one or more of the ROMP catalyst (e.g., an activecatalyst) and a ROMP monomer is encapsulated (e.g., individuallyencapsulated, in case both are encapsulated) in a capsule and exposing amodeling material formulation to the inducing condition comprisespassing the formulation through the inkjet printing heads at a shearrate that causes mechanical degradation of the capsule and release onthe encapsulated component.

In some embodiments, one or more of the ROMP catalyst (e.g., an activecatalyst) and a ROMP monomer is encapsulated (e.g., individuallyencapsulated, in case both are encapsulated) in a capsule and exposing amodeling material formulation to the inducing condition comprisesexposing the dispensed formulation to heat or radiation to thereby causedegradation of the capsule and release the encapsulated component fromthe capsule.

In some of any of the embodiments described herein, the formulationcomprises a plurality of capsules encapsulating one or both of the ROMPcomponents. The capsules can be the same or different and can releasetheir content when exposed to the same or different inducing condition.

In some of any of the embodiments described herein, the modelingmaterial formulation comprises a ROMP catalyst and a ROMP monomer, andis such that the catalyst is inactive towards initiating ROMP of themonomer upon exposure to the condition.

In these embodiments, the ROMP system consists of a ROMP monomer asdescribed herein and a latent catalyst, as defined herein, and acondition for activating the catalyst. According to these embodiments,prior to exposing the formulation to the inducing condition, thecatalyst is inactive towards initiation of ROMP of the monomer, asexplained hereinabove for a latent catalyst. The modeling materialformulation, prior to exposure to the condition, is an inactive ROMPsystem, as described herein.

In some of these embodiments, the latent catalyst is photo-activatableby, for example, exposure to radiation, as described herein, and in someembodiments the latent catalyst is thermally-activatable by, forexample, exposure to heat, as described herein.

In some of any of these embodiments, exposing the modeling materialformulation to the inducing condition comprises exposing the formulationto heat or radiation or to any other condition that activates thecatalyst, namely, converting a latent catalyst into an active catalyst.

In some of any of the embodiments described herein for the latentcatalyst, the latent catalyst can be physically separated from the ROMPmonomer, according to any one of the respective embodiments describedherein for physical separation of an active catalyst. In some of any ofthe embodiments described herein, the ROMP system comprises a ROMPmonomer as described herein, and a catalyst system that comprises apre-catalyst, as defined herein, and an activator (co-catalyst) forchemically activating the catalyst.

In some of these embodiments, the ROMP system consists of a ROMP monomeras described herein, and a catalyst system that comprises apre-catalyst, as defined herein, and an activator (co-catalyst) forchemically activating the catalyst. In such a system, the activatorchemically activates the catalyst, once it contacts the catalyst and thecatalyst initiates the ROMP, once it contacts the ROMP monomer, withouta stimulus.

In some of these embodiments, the activator is chemically active, thatis, is capable of chemically-activating the catalyst, which in turn,becomes active towards initiation of the ROMP. In these embodiments, theROMP system in the modeling material formulation is active.

In some of these embodiments, the ROMP system is rendered inactive byphysical separation between at least two of its reactive components.

In some of these embodiments, when the activator is active in theformulation, the activator is physically separated from the catalyst(e.g., the pre-catalyst) and/or the ROMP monomer in the modelingmaterial formulation. That is, the modeling material formulation is suchthat there is no contact between the activator and the catalyst, orbetween the activator and the monomer, or between the catalyst and themonomer, or between the activator and the catalyst and the monomer.Because at least two of the ROMP components composing the active ROMPsystem according to these embodiments do not contact one another, theROMP system is inactive.

According to some of these embodiments, the inducing condition rendersthe ROMP system active, at least by removing the physical separation andallowing contact between all the components composing the ROMP system.

According to some of these embodiments, the inducing condition is, orcomprises, removing the physical separation between the activator andthe catalyst (e.g., the pre-catalyst) and/or the monomer.

In some of these embodiments, the physical separation is effected byencapsulation, that is, by using a capsule (or a plurality of capsules)enveloping one or more of the catalyst, the activator and the monomer.

The capsules can be capsules individually encapsulating the activator,capsules individually encapsulating the ROMP monomer, capsulesindividually encapsulating the pre-catalyst, or any combination thereof.

The capsules can alternatively comprise capsules encapsulating a ROMPmonomer and the activator, or capsules encapsulating a ROMP monomer anda catalyst, or capsules encapsulating an activator and a catalyst. TheROMP component not included in such capsules can be individuallyencapsulated, or non-encapsulated, in the modeling material formulation.

In some of any of these embodiments, the capsule is such that releasethe ROMP component(s) encapsulated therein upon exposure to a condition.In some embodiments, exposing the modeling material to the ROMP inducingcondition comprises exposing the formulation to a condition that affectsa release of one or more of the ROMP components from a capsuleencapsulating same and results in a contact between all the reactivecomponents of the ROMP system.

Any of the embodiments described herein for degradable capsules arecontemplated for the embodiments pertaining to a modeling materialformulation that comprises a pre-catalyst and an active activator, asdescribed herein.

In some embodiments, the activator is enveloped by a degradable capsuleand is released from the capsule upon exposure to a condition thataffects degradation of the capsule and hence release of the activator.

In some of any of these embodiments, the ROMP inducing condition allowscontacting between the activator and the pre-catalyst, to therebygenerate an active catalyst, which in turn, contacts the ROMP monomerand initiates ROMP of the monomer.

In some of any of the embodiments described herein, the ROMP systemcomprises a ROMP monomer as described herein, and a catalyst system thatcomprises a pre-catalyst, as defined herein, a latent activator (latentco-catalyst) for chemically activating the catalyst, and a condition foractivating the activator towards chemically activating the catalyst.

In such a system, the activator chemically activates the catalyst andthe catalyst initiates the ROMP upon exposure to the condition.

According to these embodiments, prior to exposing the formulation to theinducing condition, the activator is inactive towards activating thecatalyst (the activator is incapable of chemically activating thecatalyst), and hence the catalyst is inactive towards initiation of ROMPof the monomer, as explained hereinabove for a latent activator in anactivator-pre-catalyst system. According to these embodiments, themodeling material formulation comprises a ROMP pre-catalyst, a ROMPmonomer, and a latent activator of the catalyst, and is such that theactivator is activatable towards activating the catalyst and thepre-catalyst is convertible to an active catalyst for initiating ROMP ofthe monomer, upon exposure to the condition. The modeling materialformulation, prior to exposure to the condition, is an inactive ROMPsystem, as described herein. The ROMP system is activated upon exposureto a condition that activates the latent activator.

In some of these embodiments, the latent activator is photo-activatableby, for example, exposure to radiation, as described herein, and in someembodiments the latent activator is thermally-activatable by, forexample, exposure to heat, as described herein.

In some of any of these embodiments, exposing the modeling materialformulation to the inducing condition comprises exposing the formulationto heat or radiation or to any other condition that activates theactivator, namely, converting a latent activator into an activeactivator, to thereby chemically activating the catalyst towardsinitiating ROMP of the ROMP monomer.

According to these embodiments, the inducing condition comprises acondition that converts a latent activator to an active activator.

In some of any of the embodiments described herein for a latentactivator, one or more of the pre-catalyst, the latent activator and theROMP monomer can be physically separated in the composition, asdescribed herein in any of the embodiments pertaining to an activeactivator.

In some of any of the embodiments described herein for single jettingsingle curing methodology, any combination of the respective embodimentsis contemplated.

In exemplary embodiments, a ROMP monomer is encapsulated, a pre-catalystis encapsulated, and the activator is a latent activator as describedherein, and can be encapsulated or not.

In other exemplary embodiments, a latent catalyst is used, and isencapsulated. In some of these embodiments, the ROMP monomer can beencapsulated or not.

In other exemplary embodiments, a latent catalyst is used, and isencapsulated or not, and the ROMP monomer is encapsulated.

In some of any of the embodiments described herein, converting a ROMPsystem to an active ROMP system is effected by two or more conditions.For example, when one or more the ROMP component is encapsulated and oneof the catalyst and the activator is latent, exposure to one conditionreleases the ROMP component from the capsule and exposure to anothercondition activates the latent component. According to theseembodiments, the ROMP inducing condition comprises a set of conditionsand exposing the formulation to these conditions can be effectedsimultaneously or sequentially. In exemplary embodiments, exposure toone condition is effected by passing the formulation through the inkjetprinting heads (application of shear forces to degrade a capsule) andexposure to another condition is application of radiation.

In some of any of the embodiments described herein, converting a ROMPsystem to an active ROMP system is effected by a single condition. Forexample, a latent catalyst which is photoactivatable can be used incombination with a ROMP monomer that is encapsulated by photodegradablecapsules (which undergo degradation upon exposure to radiation such asUV radiation). In another example, a pre-catalyst and/or a ROMP monomerare encapsulated in photodegradable capsules and a latent activator thatis photoactivatable is used. In such embodiments, and similarembodiments, a UV-activatable ROMP system is provided in the modelingmaterial formulation.

In additional exemplary embodiments, a latent catalyst which isthermally-activatable can be used in combination with a ROMP monomerthat is encapsulated by thermally-degradable capsules (which undergodegradation upon exposure to heat). In another example, a pre-catalystand/or a ROMP monomer are encapsulated in thermally-degradable capsulesand a latent activator that is thermally-activatable is used. In suchembodiments, and similar embodiments, a thermally-activatable ROMPsystem is provided in the modeling material formulation.

In some of any of the embodiments described herein for single jettingsingle curing methodology, the modeling material can further comprise aROMP inhibitor, as described herein.

In some of any of the embodiments described herein for the “singlejetting single curing” methodology, the modeling material formulationcan comprise, in addition to the ROMP components, additional,non-curable (non-reactive) materials, as described in further detailhereinunder.

Single Jetting Multi-Curing (e.g., Dual Curing):

According to some embodiments of the present invention, a modelingmaterial formulation as described herein for any one of the embodimentsof “single jetting single curing” further comprises one or more curablesystems which undergo polymerization and/or curing via a non-ROMPreaction.

A non-ROMP reaction refers to any polymerization and curing reactionsthat do not involve ROMP. Such reactions include, for example, chaingrowth polymerization such as free-radical polymerization, cationicpolymerization, anionic polymerization, and step-growth polymerizationsuch as polycondensation.

In some embodiments, a curable system which undergoes polymerizationand/or curing via a non-ROMP reaction, as described herein, comprisesmonomers and/or oligomers which are polymerizable by a non-ROMP reactionas described herein. Such materials are also collectively referred toherein as non-ROMP polymerizable materials or monomers, or non-ROMPcurable materials or monomers.

A curable system which undergoes polymerization and/or curing via anon-ROMP reaction can alternatively, or in addition, compriseshort-chain polymeric materials which undergo curing by, for example,cross-linking, whereby the curing comprises free-radical cross-linking,cationic or anionic cross-linking, and/or polycondensation. Suchmaterials are also encompassed herein by the expressions non-ROMPpolymerizable materials or monomers, or non-ROMP curable materials ormonomers.

A curable system which undergoes polymerization and/or curing via anon-ROMP reaction may comprise one or more curable materials thatundergo polymerization and/or curing via a non-ROMP reaction, andoptionally one or more initiators for initiating a respective non-ROMPreaction. In some embodiments, such a system further comprises acondition for inducing initiation of the non-ROMP reaction.

A curable system which undergoes polymerization and/or curing via anon-ROMP reaction is also referred to herein as a non-ROMP curablesystem.

In some of these embodiments, the modeling material further comprises,in addition to the ROMP components described for the single curingapproach, one or more curable materials that undergo polymerizationand/or curing via a non-ROMP reaction, and optionally one or moreinitiators for initiating a respective non-ROMP reaction.

In some of any of the embodiments pertaining to a dual curing approach,the method further comprises exposing the modeling material formulationto a condition for inducing initiation of a respective polymerizationand/or curing via a non-ROMP reaction.

In some embodiments, the condition for inducing polymerization and/orcuring via a non-ROMP reaction is the same as the ROMP indictingcondition, and in some embodiments, it is a different condition.

When the condition is different from the ROMP inducing condition,exposure to the conditions can be effected simultaneously orsequentially. The order can be determined as desired, by any personskilled in the art.

In some of any of the embodiments described herein, one or more of thecomponents of a curable system (e.g., a non-ROMP curable material and/oran initiator of a respective non-ROMP reaction) and/or one or more ofthe ROMP components in the modeling material formulation is/arephysically separated from the other components in the formulation.

In some of these embodiments, one or more of the ROMP components, e.g.,a ROMP monomer, a ROMP active catalyst, a ROMP latent catalyst, a ROMPpre-catalyst and/or a ROMP activator (latent or not), if present, isphysically separated from other components in the modeling materialformulation.

Alternatively, or in addition, one or more of the non-ROMP curablesystems, e.g., a non-ROMP curable monomer and/or a respective initiatorand/or activator, is physically separated from other components in themodeling material formulation.

In some of any of these embodiments, the physical separation can be, forexample, by means of a capsule enveloping the component, and the capsuleis such that releases the enveloped component upon exposure to thecondition that induced curing (a ROMP inducing condition or anothercuring condition).

The capsule and corresponding conditions for releasing an envelopedcomponent and thereby initiating curing, can be in accordance with anyof the embodiments described herein for a ROMP system.

In embodiments where two or components are individually encapsulated,the capsules can be degradable upon exposure to the same or differentcondition for initiating curing.

In a non-limiting example, a modeling material formulation for a singlejetting dual curing methodology can comprise a ROMP monomer, a ROMPactive catalyst, a non-ROMP curable monomer and a non-ROMP initiator,whereby the ROMP active catalyst is encapsulated.

In another example, a modeling material formulation for a single jettingdual curing methodology can comprise a ROMP monomer, a ROMP latent oractive catalyst, a non-ROMP curable monomer and a non-ROMP initiator,whereby the ROMP latent catalyst is encapsulated and the non-ROMPinitiator are individually encapsulated. The capsules of the ROMPcatalyst and the non-ROMP initiator can be the same or different, andthe condition for degrading the capsules and releasing the encapsulatedcomponent can be the same or different.

Any other combinations of encapsulated and non-encapsulated componentsin a dual curing methodology are contemplated.

In some of any of the embodiments described herein, the non-ROMP curablesystem is polymerizable or curable by free radical polymerization. Insome of these embodiments, the modeling material formulation comprises,in addition to a selected inactive ROMP system as described herein inany of the respective embodiments, a monomer and/or oligomer that ispolymerizable by a free radical polymerization and a free radicalinitiator.

In some of any of the embodiments described herein, the non-ROMP curablesystem is polymerizable or curable by cationic polymerization. In someof these embodiments, the modeling material formulation comprises, inaddition to a selected inactive ROMP system as described herein in anyof the respective embodiments, a monomer and/or oligomer that ispolymerizable by a cationic polymerization and a cationic initiator.

In some of any of the embodiments described herein, the non-ROMP curablesystem is polymerizable or curable by anionic polymerization. In some ofthese embodiments, the modeling material formulation comprises, inaddition to a selected inactive ROMP system as described herein in anyof the respective embodiments, a monomer and/or oligomer that ispolymerizable by anionic polymerization and an anionic initiator.

In some of any of the embodiments described herein, the non-ROMPinitiator is a latent initiator, which is activatable upon exposure to acuring condition, as described herein.

In some of any of the embodiments described herein, the non-ROMPinitiator is chemically activatable by an activator, similarly to theROMP pre-catalysts and activators described herein. In some of theseembodiments, the modeling material formulation further comprises such anactivator for chemically activating the non-ROMP initiator. Theactivator in the formulation can be a latent activator which isactivatable upon exposure to a curing condition. The activator canalternatively physically separated, as described herein, from othernon-ROMP components in the formulation. The activator, latent or not,can be the same activator that chemically activates a ROMP pre-catalystor can be a different activator.

In some of any of the embodiments described herein, the non-ROMP curablesystem is a photo-polymerizable or photo-activatable system, whichundergoes polymerization and/or curing upon exposure to radiation as acuring condition. The radiation in these embodiments may affect one ormore of initiation of a non-ROMP reaction by activating a latentinitiator; initiation of a non-ROMP reaction by activating a latentactivator; and/or releasing one or more encapsulated components of thesystem.

In some of these embodiments, the ROMP system in the formulation is aphoto-activatable system, as described herein.

In some of these embodiments, the radiation required for curing the ROMPsystem and the non-ROMP system is the same (e.g., UV radiation).

In some of these embodiments, a modeling material formulation is curedupon exposure to radiation as a single condition for inducing curing ofthe formulation.

Exemplary non-ROMP curable systems and formulations that can be combinedwith ROMP components for the single jetting dual curing or multi-curingmethodology are described on further detail hereinunder.

In some of any of the embodiments described herein, a ROMP monomer issuch that further comprises a group that is polymerizable by a non-ROMPreaction. Such monomers are referred to herein as dual-curing monomersor oligomers or materials.

For example, a ROMP monomer which is a strained cyclic olefin asdescribed herein, can be substituted by an acrylate- ormethacrylate-containing group, that can undergo free-radicalpolymerization. Exemplary such monomers are dicyclopentenyl acrylates,such as, for example, Fancryl FA511 AS, FA512AS, marketed by Hitachi,which contain an acrylic functional group and cyclic olefin structureenabling dual polymerization of the same compound using free radicalmechanism and ROMP mechanism, respectively.

Other examples for dual-curing monomers are epoxy norbornenederivatives, such as, for example, described in U.S. Pat. Nos. 8,362,171and 7,728,090, which are incorporated by reference as if fully set forthherein.

Multi-Jetting (e.g., Dual Jetting):

In some of any of the embodiments described herein, the buildingmaterial comprises two or more modeling material formulations which aredispensed from different inkjet printing heads (each formulation isjetted from a different printing head or a different set of printingheads) to form the layers.

Such a methodology, which is referred to herein as dual jetting, whentwo different modeling material formulations are used, or asmulti-jetting, when more than two modeling material formulations areused, allows dispensing modeling material formulations which are absentof one or more of the components required for a polymerization or curingto occur, whereby when the formulations are dispensed and contact oneanother, curing and/or polymerization occurs.

In the context of some of the present embodiments, such a methodologyallows separating ROMP components as described herein by including adifferent combination of components in each formulation, whereby none ofthe formulations comprises all the components required for the ROMPreaction to occur. According to these embodiments, a ROMP reaction, andoptionally non-ROMP reactions, occur only on the receiving medium, andafter the building material is dispensed.

In some of these embodiments, exposing the formulation to a conditionfor initiating ROMP can be effected by contacting the differentformulations on the receiving medium (receiving tray). In some of theseembodiments, exposing to a ROMP inducing condition is effected bydispensing the formulations.

Connex 3™ (Stratasys Ltd., Israel) multiple material depositiontechnology, is an exemplary technology that provides the possibility toseparate the components of a polymerizable or curable system intodifferent formulations. Objet Connex 3™ (Stratasys Ltd., Israel)multiple material deposition system, is a system that allows utilizingsuch a technology.

In some of any of these embodiments, the building material comprises twoor more modeling material formulations, and the two or more modelingmaterial formulations are such that when combined, curing is effected byROMP reaction. These embodiments are referred to herein as dual jettingsingle curing or multi jetting single curing methodology.

In some of any of these embodiments, the building material comprises twoor more modeling material formulations, and the two or more modelingmaterial formulations are such that when combined, curing is effected byboth a ROMP reaction and a non-ROMP reaction, as defined herein. Theseembodiments are referred to herein as dual jetting dual curing or multijetting multi-curing methodology.

Multi-Jetting (e.g., Dual Jetting) Single Curing:

In some of any of these embodiments, the building material comprises twoor more modeling material formulations, and the two or more modelingmaterial formulations are such that when combined, curing is effected byROMP reaction.

In some of these embodiments, each of the modeling material formulationscomprises a ROMP monomer (which can be the same or different).

In some of any of the embodiments pertaining to multi-jetting singlecuring, any of the ROMP systems described hereinabove for single-jettingsingle curing can be used, whereby a different combination of the ROMPcomponents of a respective system is included in each of the modelingmaterial formulations.

In some of these embodiments, each of the modeling material formulationscomprises a ROMP monomer (which can be the same or different), and oneof the formulations further comprises a ROMP catalyst.

In some of these embodiments, the building material comprises more thantwo the modeling material formulations, each independently comprising aROMP monomer (which can be the same or different), and one or two ofthese formulations further comprises a ROMP catalyst.

In some of any of these embodiments, one or more of the modelingmaterial formulations is devoid of a ROMP catalyst, and in someembodiments, one or more of the modeling material formulations comprisesa ROMP monomer and a ROMP catalyst.

In some of these embodiments, one or more of the ROMP catalysts is anactive catalyst, as described herein.

In some of these embodiments, the formulations comprise two or moretypes of catalysts.

In exemplary embodiments, the two or more catalysts are activecatalysts.

In some of these embodiments, the formulations comprise two or moretypes of ROMP monomers.

In some of these embodiments, each of the ROMP active catalysts has adifferent reactivity towards initiation of ROMP of the differentmonomers.

In some exemplary embodiments, a ROMP system of the modeling materialformulations comprises first and second ROMP monomers, and first andsecond ROMP active catalysts. The first ROMP active catalyst has ahigher reactivity towards initiation of ROMP of the first monomer, andthe second ROMP active catalyst has a higher reactivity towardsinitiation of ROMP of the second monomer.

In some of these embodiments, one of the formulations comprises a firstROMP monomer and the second active catalyst that is less reactivetowards initiation of ROMP of the first monomer and has a higherreactivity towards initiation of ROMP of the second ROMP monomer, andanother one of the formulations comprises the first active catalyst thatis less reactive towards initiation of ROMP of the second ROMP monomerand has a higher reactivity towards initiation of ROMP of the first ROMPmonomer.

Such exemplary embodiments allow using active catalysts while avoidingsubstantial clogging of the inkjet printing heads.

In some of any of the embodiments described herein, the ROMP catalyst(s)include one or more latent catalysts, which are activatable uponexposure to a ROMP inducing condition, as described herein.

A method, according to these embodiments, comprises exposing thedispensed layers to a condition that activates the catalyst, asdescribed herein.

In some embodiments, the ROMP system further comprises an activator andthe catalyst is a pre-catalyst.

In some of these embodiments, each of the modeling material formulationsindependently comprises a ROMP monomer, one or more of the formulationsfurther comprise a pre-catalyst, and one or more other formulationsfurther comprise an activator. In some of these embodiments, the one ormore formulations that comprise the activator are devoid of thepre-catalyst. In some embodiments, the one or more formulations thatcomprise the pre-catalyst are devoid of an activator.

In some of these embodiments, exposing the dispensed layers to inducingcondition is effected by the contacting the formulations on thereceiving medium, and hence comprises the formation of the dispensedlayers (e.g., by jetting the modeling material formulation by the inkjetprinting heads).

In some of any of the embodiments described herein, the ROMP systemcomprises a latent activator.

In some of these embodiments, exposing the dispensed layers to inducingcondition is effected by exposing the dispensed formulations to acondition that activates the activator.

In some of any of the embodiments described herein, one or more of thecomponents in one or more of the formulations is physically separatedfrom the other components in the formulation, as described herein in thecontext of the single jetting single curing embodiments.

In some of any of the embodiments described herein, one or more, oreach, of the modeling material formulations further comprises a ROMPinhibitor.

In some of any of the embodiments described herein, one or more, oreach, of the modeling material formulations, further comprisesadditional materials, as is described in further detail hereinunder.

In some of any of the embodiments described herein, converting the ROMPsystem or systems to active ROMP systems is effected by a singlecondition. For example, in some embodiments, activating of a latentcatalyst, if present in one or more of the formulations, of a latentactivator, if present in one or more of the formulations, and/or releaseof one or more components that are encapsulated (e.g., degradation ofcapsules enveloping a ROMP component, if present in one or more of theformulations, are all effected upon exposing the dispensed formulationsto the same condition. The condition can be, for example, radiation(e.g., UV radiation), such that the ROMP system or systems in the two ormore modeling material formulations is/are photoactivatable. Thecondition can be, for example, heat, such that the ROMP system orsystems in the two or more modeling material formulations is/arethermally-activatable.

Multi (e.g., Dual) Jetting Multi (e.g., Dual) Curing:

In some of the embodiments described herein pertaining to multi-curingor dual curing, the two or more modeling material formulations comprise,in addition to ROMP components, components of one or more non-ROMPcurable systems, as described herein (for example, under “single jettingmulti-curing”).

The components of such a building material therefore undergopolymerization and/or curing via ROMP polymerization and also by one ormore non-ROMP reactions, as described herein.

In some of these embodiments, the components of the two or more modelingmaterial formulations form two curable systems, for example, one or moreROMP systems and one or more of free radial polymerization system,cationic polymerization system, anionic polymerization system, etc. Anypolymerization system that is usable in 3D inkjet printing iscontemplated.

In some of any of these embodiments, the ROMP components can include oneor more ROMP monomers and one or more catalysts, for example, activecatalysts.

In some of the embodiments when an active catalyst is used, the activecatalyst is included in a modeling material formulation that is devoidof a ROMP monomer, and which, in some embodiments, comprises a materialthat polymerizable by a non-ROMP reaction (a non-ROMP curable orpolymerizable material) as described herein.

In some of the embodiments when an active catalyst is used, one or moreof the modeling material formulations comprises a ROMP monomer ormonomers, and is devoid of a catalyst, and other one or more modelingmaterial formulation comprises a ROMP catalyst which is an activecatalyst, and is devoid of a ROMP monomer.

Alternatively, in any one of these embodiments, the catalyst is a latentcatalyst.

Further alternatively, in any one of these embodiments, the catalyst isphysically separated from the other components in the formulationcontaining same. Physical separation can be effected by means ofdegradable capsules, as described herein.

In any one of the embodiments when a latent catalyst is used, theinducing condition comprises a condition which activates the catalyst,as described herein.

In any one of the embodiments when an encapsulated catalyst is used, theinducing condition comprises a condition which degrades the capsule soas to release the active catalyst.

Alternatively, in any one of these embodiments, the catalyst is apre-catalyst and the one or more of the modeling material formulationscomprises an activator or a latent activator, as described herein.

In some of these embodiments, one or more of the modeling materialformulations comprise a ROMP monomer and a pre-catalyst and other one ormore modeling material formulations comprise the activator.Alternatively, one or more of the modeling material formulationscomprise a ROMP monomer and the activator and other one or more modelingmaterial formulations comprise the pre-catalyst.

Whenever the activator is included in the formulation(s) as activetowards chemically activating the pre-catalyst to provide an activecatalyst, the inducing condition for effecting ROMP can be contactingthe respective formulations on the receiving medium (tray). Thus,exposing to the condition is effected by jetting the formulations by theinkjet printing heads (dispensing the layers of the formulations).

Further alternatively, one or more of the modeling material formulationscomprise a ROMP monomer and other one or more modeling materialformulations comprise the activator and the pre-catalyst. In some ofthese embodiments, the activator is a latent activator and/or one orboth of the activator and the pre-catalyst are physically separated fromone another, as described herein.

In some of any of the embodiments described herein, one or more of themodeling material formulations further comprises a non-ROMP curablematerial (a material polymerizable or curable by a non-ROMP reaction asdescribed herein).

In some of these embodiments, the non-ROMP curable material is includedin a formulation which comprises a ROMP catalyst (active, latent orpre-catalyst, encapsulated or non-encapsulated) and/or a ROMP activator(active or latent, encapsulated or non-encapsulated).

In some of these embodiments, one or more formulations comprise a ROMPmonomer and one or more other formulations comprise a non-ROMP curablematerial and a ROMP catalyst (active, latent or pre-catalyst,encapsulated or non-encapsulated) and/or a ROMP activator (active orlatent, encapsulated or non-encapsulated), and is devoid of a ROMPmonomer.

In exemplary embodiments of a dual jetting methodology, one modelingmaterial formulation, formulation A, comprises a ROMP monomer andanother modeling material formulation, formulation B comprises anon-ROMP curable material.

In some embodiments, formulation A further comprises a ROMP pre-catalyst(optionally encapsulated) and formulation B further comprises a ROMPactivator (latent or not, encapsulated or non-encapsulated). In someembodiments, formulation A further comprises a ROMP activator (latent ornot, optionally encapsulated) and formulation B further comprises a ROMPpre-catalyst (optionally encapsulated). In some embodiments, formulationB further comprises a ROMP catalyst (latent or active, optionallyencapsulated). In some embodiments, formulation B further comprises aROMP activator (latent or not, encapsulated or non-encapsulated) and aROMP pre-catalyst (optionally encapsulated).

Other combinations are also contemplated. For example, in any of theformulations described herein for the multi-jetting single curingmethodology, a ROMP monomer in one or more of the modeling materialformulations can be replaced by a non-ROMP curable material.

In some of any of the embodiments described herein, one or more of themodeling material formulations, according to any one of the embodimentsdescribed herein and any combination thereof, further comprises aninitiator of the non-ROMP reaction (a non-ROMP initiator).

In some of these embodiments, the initiator is comprised in one or moremodeling material formulations which are devoid of a non-ROMP curablematerial. In some embodiments, one or more of the modeling materialformulations comprise a ROMP monomer and a non-ROMP initiator. In someembodiments, such a formulation is devoid of one or more of the ROMPcomponents of the ROMP system (e.g., a catalyst, an activator, apre-catalyst).

In exemplary embodiments of a dual jetting methodology according tothese embodiments, one modeling material formulation, formulation A,comprises a ROMP monomer and another modeling material formulation,formulation B comprises a non-ROMP curable material. In someembodiments, formulation A further comprises a ROMP pre-catalyst(optionally encapsulated) and a non-ROMP initiator (latent or active,optionally encapsulated), and formulation B further comprises a ROMPactivator (latent or not, encapsulated or non-encapsulated). In someembodiments, formulation A further comprises a ROMP activator (latent ornot, optionally encapsulated) and a non-ROMP initiator (latent oractive, optionally encapsulated), and formulation B further comprises aROMP pre-catalyst (optionally encapsulated). In some embodiments,formulation A further comprises a non-ROMP initiator (latent or active,optionally encapsulated) and formulation B further comprises a ROMPcatalyst (latent or active, optionally encapsulated). In someembodiments, formulation A further comprises a ROMP activator (latent ornot, optionally encapsulated) and a non-ROMP initiator (latent oractive, optionally encapsulated), and formulation B further comprises aROMP activator (latent or not, encapsulated or non-encapsulated) and aROMP pre-catalyst (optionally encapsulated).

Other combinations are also contemplated. For example, in any of theformulations described herein for the multi-jetting single curingmethodology, a ROMP monomer in one or more of the modeling materialformulations can be replaced by a non-ROMP curable material, and one ormore of the formulations further comprises a non-ROMP initiator (latentor active, optionally encapsulated).

In some of any of the embodiments described herein, the method furthercomprises exposing the formulation to one or more conditions forinducing polymerization and/or curing of the one or more non-ROMPcurable systems. In some embodiments, the condition for inducing ROMPand the condition for inducing polymerization and/or curing of thenon-ROMP curable material(s) are the same. In some embodiments, theconditions are different and can be applied simultaneously orsequentially, as desired or required.

Curable Systems:

A “curable system” as described herein refers to a system that comprisesone or more curable materials, as defined herein.

In some of any of the embodiments described herein, a “curable system”comprises one or more curable materials and optionally one or moreinitiators and/or catalysts for initiating curing of the curablematerials, and, further optionally, one or more conditions (alsoreferred to herein as curing conditions) for inducing the curing, asdescribed herein.

In some of any of the embodiments described herein, a curable materialis a monomer or a mixture of monomers and/or an oligomer or a mixture ofoligomers which can form a polymeric material upon a polymerizationreaction, when exposed to a condition at which curing, as definedherein, occurs (a condition that affects or induces curing).

A “bifunctional” or “multifunctional” curable material or monomer ismeant to describe curable materials that result in a polymeric materialthat features two or more functional groups, and hence can act also as across-linker, for cross-linking polymeric chains formed of the sameand/or different curable materials in the building material.

In some embodiments, a curable system further comprises an initiator forinitiating the curing and/or polymerization of the curable material(s).The initiator can be active towards the initiation of the curing and/orpolymerization in the curable system or can be inactive towards thisinitiation.

Inactive initiators can be latent initiators, which are activatable uponexposure to a condition, and this condition induces the curing and/orpolymerization.

Alternatively, inactive initiators can be inactive due to physicalseparation from the curable material(s). The physical separation can beeffected by means of capsules, preferably degradable capsules asdescribed herein. Such initiators are activatable by a condition thatremoves the physical separation, e.g., induces release of the initiatorfrom the capsule, as described herein.

Further alternatively, inactive initiators can be chemically activatedby an activator, and become active upon a condition that results incontacting the activator, similarly to any of the embodiments describedherein in the context of a pre-catalyst and an activator.

In some of any of the embodiments described herein, depending on itscomponents and chemistry, a curable system further requires a conditionfor effecting curing and/or polymerization of the curable materials.

In some of any of the embodiments described herein, the one or moremodeling material formulations comprise a curable system that is anactive system, namely, the components included in the one or moremodeling material formulations can undergo polymerization or curingwithout a stimulus.

In some of any of the embodiments described herein, the one or moremodeling material formulation comprise a curable system that isinactive, namely, the components included in the one or more modelingmaterial formulations can undergo polymerization or curing only whenexposed to a condition that induces curing.

A curable system as described herein may comprise, in addition to acurable material, an initiator and optionally an activator.

A curable system as described herein can be a ROMP system, as describedherein in any of the respective embodiments, which comprises one or moreROMP monomers, as described herein in any of the respective embodiments.

In embodiments pertaining to dual or multi-curing, along with singlejetting, namely, the modeling material formulation comprises in additionto components of a ROMP system, components of one or more additionalcurable systems, which are referred to herein also as non-ROMP systems.

In embodiments pertaining to dual or multi-curing, along with dual ormulti-jetting, the two or more modeling material formulations furthercomprise components of additional, one or more curable systems, eitherin the same, and preferably, in different formulations.

Herein throughout, curable systems which comprise curable materials thatare curable and/or polymerizable via a polymerization or curing reactionother than ROMP, are referred to herein also as non-ROMP curablesystems. The components of such systems are also referred to herein asnon-ROMP components, for example, non-ROMP curable materials, non-ROMPinitiators, non-ROM-activators, and non-ROMP inducing condition (orcondition for inducing non-ROMP polymerization and/or curing or forinitiating a non-ROMP reaction).

In some of any of the embodiments described herein, a concentration of acurable material, including a ROMP monomer, in a modeling materialformulation containing same ranges from about 50% to about 99% by weightof the total weight of the modeling material formulation, including anysubranges and intermediate values therebetween.

In some of these embodiments, a modeling material formulation comprisesa single curable material, at the indicted concentration range.

In some of these embodiments, a modeling material formulation comprisestwo or more curable materials, and the total concentration of curablematerials ranges from about 50% to about 99% by weight of the totalweight of the formulation.

In some of any of the embodiments described herein, a concentration ofadditional reactive components in a curable system as described herein,including, for example, a ROMP catalyst, a ROMP activator, a non-ROMPinitiator, a non-ROMP activator (or co-initiator), in a modelingmaterial formulation containing same individually ranges (for eachcomponent) from about 0.001% to about 10%, or from about 0.01% to 5% byweight of the total weight of the modeling material formulation,including any subranges and intermediate values therebetween.

In some embodiments, a concentration of a ROMP catalyst (active orlatent) or a ROMP pre-catalyst in a modeling material formulationcontaining same independently ranges from about 0.001% to about 1%, orfrom about 0.001% to about 0.1% by weight of the total weight of themodeling material formulation, including any subranges and intermediatevalues therebetween.

In some embodiments, a concentration of a ROMP inhibitor in a modelingmaterial formulation containing same independently ranges from about0.001% to about 1%, or from about 0.001% to about 0.1% by weight of thetotal weight of the modeling material formulation, including anysubranges and intermediate values therebetween.

In some embodiments, a concentration of a ROMP activator (active orlatent) in a modeling material formulation containing same independentlyranges from about 0.001% to about 5%, or from about 0.001% to about 1%by weight of the total weight of the modeling material formulation,including any subranges and intermediate values there between. In someof these embodiments, a modeling material formulation comprises a singlereactive component, at the indicted concentration range.

In some of these embodiments, a modeling material formulation comprisestwo or more curable materials reactive components, and the totalconcentration of the reactive components materials ranges from about0.001% to about 10% by weight of the total weight of the formulation,including any subranges and intermediate values therebetween.

In some of any of the embodiments described herein, components whichform a curable system as described herein are referred to as reactivecomponents or materials, and curable components are referred to asreactive polymerizable components, materials, monomers, or groups,interchangeably.

In some of any of the embodiments described herein, a curable materialcan be a monofunctional curable material, which comprises onepolymerizable group that participates in the polymerization or curing,or a bifunctional or multifunctional curable material, as definedherein.

Additional components included in the modeling material formulations asdescribed herein, which do not undergo a polymerization and/or curing,are also referred to herein as non-reactive materials or components.

Non-ROMP curable systems according to some of the present embodiments,can be, for example, curable systems in which the non-ROMP curablematerial(s) undergo curing and/or polymerization via free radicalpolymerization. Such systems are also referred to herein as free-radicalcurable systems.

Any free-radical curable system that is usable in 3D inkjet printingprocesses and systems is contemplated by these embodiments.

In some embodiments, free-radical polymerizable (curable) components mayinclude mono-functional and/or multi-functional acrylic and/ormethacrylic monomers, acrylic and/or methacrylic oligomers, and anycombination thereof. Other free-radical polymerizable compounds mayinclude thiols, vinyl ethers and other components (monomers oroligomers) with a reactive double bond.

An acrylic or methacrylic oligomer can be, for example, a polyester ofacrylic acid or methacrylic acid, oligomers of urethane acrylates andurethane methacrylates. Urethane-acrylates are manufactured fromaliphatic or aromatic or cycloaliphatic diisocyanates or polyisocyanatesand hydroxyl-containing acrylic acid esters. Oligomers may bemono-functional or multifunctional (for example, di-, tri-,tetra-functional, and others). An example is a urethane-acrylateoligomer marketed by IGM Resins BV (The Netherlands) under the tradename Photomer-6010.

An acrylic or methacrylic monomer can be, for example, an ester ofacrylic acid or methacrylic acid. Monomers may be mono-functional ormultifunctional (for example, di-, tri-, tetra-functional, and others).An example of an acrylic mono-functional monomer is phenoxyethylacrylate, marketed by Sartomer Company (USA) under the trade nameSR-339. An example of an acrylic di-functional monomer is propoxylated(2) neopentyl glycol diacrylate, marketed by Sartomer Company (USA)under the trade name SR-9003.

Either the monomer or the oligomer might be polyfunctional, and can be,for example, Ditrimethylolpropane Tetra-acrylate (DiTMPTTA),Pentaerythitol Tetra-acrylate (TETTA), Dipentaerythitol Penta-acrylate(DiPEP). Any other curable material that is polymerizable by freeradical polymerization is contemplated.

In some embodiments, a free-radical polymerizable material ispolymerizable or curable by exposure to radiation. Systems comprisingsuch a material can be referred to as photo-polymerizable free-radicalsystems, or photoactivatable free-radical systems.

In some embodiments, a free-radical curable system further comprises afree radical initiator, which produces free radicals for initiating thepolymerization and/or curing.

In some embodiments, a condition for initiating free-radical curingand/or polymerization comprises is a condition that induced free radicalgeneration by the initiator. The initiator in such cases is a latentinitiator, which produces free radicals when exposed to the condition.

In some embodiments, the initiator is a free-radical photoinitiator,which produces free radicals when being exposed to radiation.

In some of any of the embodiments described herein for free-radicalcurable systems, the radiation is UV radiation, and the system is aUV-curable system.

A free-radical photoinitiator may be any compound that produces a freeradical on exposure to radiation such as ultraviolet or visibleradiation and thereby initiates a polymerization reaction. Non-limitingexamples of suitable photoinitiators include benzophenones (aromaticketones) such as benzophenone, methyl benzophenone, Michler's ketone andxanthones; acylphosphine oxide type photo-initiators such as2,4,6-trimethylbenzolydiphenyl phosphine oxide (TMPO),2,4,6-trimethylbenzoylethoxyphenyl phosphine oxide (TEPO), andbisacylphosphine oxides (BAPO's); benzoins and bezoin alkyl ethers suchas benzoin, benzoin methyl ether and benzoin isopropyl ether and thelike. Examples of photoinitiators are alpha-amino ketone, andbisacylphosphine oxide (BAPO's).

A free-radical photo-initiator may be used alone or in combination witha co-initiator. Co-initiators are used with initiators that need asecond molecule to produce a radical that is active in the photocurablefree-radical systems. A co-initiator of a photoinitiator is alsoreferred to herein as a non-ROMP activator. Benzophenone is an exampleof a photoinitiator that requires a second molecule, such as an amine,to produce a free radical. After absorbing radiation, benzophenonereacts with a ternary amine by hydrogen abstraction, to generate analpha-amino radical which initiates polymerization of acrylates.Non-limiting example of a class of co-initiators are alkanolamines suchas triethylamine, methyldiethanolamine and triethanolamine.

Representative examples of UV curable materials of a free-radicalcurable system include, but are not limited to, tricyclodecanedimethanol diacrylate SR 833S, Phenoxy ethyl Acrylate SR 339, Isobornylacrylate SR 506D and etc. Other examples are provided in Table 2 herein.

In some of any of the embodiments described herein, one or more of themodeling material formulations containing a free-radical curable systemcomprises a radical inhibitor, for preventing or slowing downpolymerization and/or curing prior to exposing to the curing condition.

In some of any of the embodiments described herein, the one or moreadditional curable systems is/are polymerizable or cured via cationicpolymerization, and are referred to herein also as cationicpolymerizable or cationic curable systems.

The curable components or materials of such systems undergopolymerization or curing via cationic polymerization.

Exemplary cationically polymerizable components include, but are notlimited to, epoxy-containing materials (monomers or oligomers),caprolactams, caprolactones, oxetanes, and vinyl ethers (monomers oroligomers).

Non-limiting examples of epoxy-containing curable compounds includeBis-(3,4 cyclohexylmethyl) adipate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carboxylate, 1,2epoxy-4-vinylcyclohexane, 1,2-epoxy hexadecane, 3,4-epoxycyclohexylmethyl-3,4-epoxy cyclohexane carboxylate, which is available,for example, under the trade name UVACURE 1500 from Cytec SurfaceSpecialties SA/NV (Belgium) and mono or multifunctional silicon epoxyresins such as PC 1000 which is available from Polyset Company (USA).

In some embodiments, a cationic polymerizable material is polymerizableor curable by exposure to radiation. Systems comprising such a materialcan be referred to as photo-polymerizable cationic systems, orphotoactivatable cationic systems.

In some embodiments, a cationic curable system further comprises acationic initiator, which produces cations for initiating thepolymerization and/or curing.

In some embodiments, a condition for initiating cationic curing and/orpolymerization comprises is a condition that induced cation generationby the initiator. The initiator in such cases is a latent initiator,which produces cations when exposed to the condition.

In some embodiments, the initiator is a cationic photoinitiator, whichproduces cations when exposed to radiation.

In some of any of the embodiments described herein for cationic curablesystems, the radiation is UV radiation, and the system is a cationicUV-curable system.

Suitable cationic photoinitiators include, for example, compounds whichform aprotic acids or Bronsted acids upon exposure to ultraviolet and/orvisible light sufficient to initiate polymerization. The photoinitiatorused may be a single compound, a mixture of two or more activecompounds, or a combination of two or more different compounds, i.e.co-initiators. Non-limiting examples of suitable cationicphotoinitiators include aryldiazonium salts, diaryliodonium salts,triarylsulphonium salts, triarylselenonium salts and the like. Anexemplary cationic photoinitiator is a mixture of triarylsolfoniumhexafluoroantimonate salts.

Non-limiting examples of suitable cationic photoinitiators includeP-(octyloxyphenyl) phenyliodonium hexafluoroantimonate UVACURE 1600 fromCytec Company (USA), iodonium(4-methylphenyl)(4-(2-methylpropyl)phenyl)-hexafluorophosphate known asIrgacure 250 or Irgacure 270 available from Ciba Speciality Chemicals(Switzerland), mixed arylsulfonium hexafluoroantimonate salts known asUVI 6976 and 6992 available from Lambson Fine Chemicals (England),diaryliodonium hexafluoroantimonate known as PC 2506 available fromPolyset Company (USA), (tolylcumyl) iodonium tetrakis(pentafluorophenyl) borate known as Rhodorsil® Photoinitiator 2074available from Bluestar Silicones (USA), iodoniumbis(4-dodecylphenyl)-(OC-6-11)-hexafluoro antimonate known as Tego PC1466 from Evonik Industries AG (Germany). Exemplary cationicphotoinitiators are also presented, for example, in Tables 2, 3, 5, and9.

In some of any of the embodiments described herein, the non-ROMP curablesystem is any other system that is usable in 3D-printing processes andsystems. Additional examples include, without limitation, systems basedon polyurethane chemistry, in which isocyanate-containing compounds andhydroxyl-containing compounds (e.g., polyols) react via polycondensationin the presence of a catalyst and/or upon exposure to UV radiation,),thiol chemistry, in which mercaptopropionate-based curable materialspolymerize when exposed to UV in the presence of a free-radicalphotoinitiator, and more.

In some of any of the embodiments described herein, the non-ROMP curablesystems comprise a combination of two or more non-ROMP curable systems.

In some of any of the embodiments described herein, at least one, andpreferably each, of the non-ROMP curable systems in the modelingmaterial formulations described herein is activatable upon exposure tothe same condition as does a ROMP system. That is, curing of all thecurable systems is effected upon exposure to the same curing inducingcondition, as described herein.

In some of these embodiments, the ROMP system is a photoactivatablesystem and the one or more non-ROMP curable systems are alsophotoactivatable systems.

In some of these embodiments, the systems are UV-curable, that is, thecondition inducing curing is effected by exposure to UV radiation, asdescribed herein.

Photoactivatable ROMP systems are described herein.

Photoactivatable non-ROMP systems may include free radicalphotopolymerizable compounds (e.g., Tricyclodecane dimethanol diacrylateSR 833S, Phenoxy ethyl Acrylate SR 339, Isobornyl acrylate SR 506D andso on), and/or cationic polymerizable compounds (e.g., cycloaliphaticepoxide Uvacure 1500, epoxidized polybutadiene polyBD605E, limonenedioxide Celloxide 3000, Difunctional silicon-containing epoxy resinPC2000, etc.), optionally in combination with a free radicalphotoinitiator or a cationic photoinitiator, respectively, as describedherein.

In some of any of the embodiments described herein, when a curablesystem is photoactivatable, a modeling material formulation can furthercomprise a photosensitizer.

In dual or multi jetting methodologies, the photosensitizer can beincluded in a modeling material formulation that comprises a respectivephotocurable material (including a ROMP monomer) or in anotherformulation, that is devoid of the photocurable material. In someembodiments, the photosensitizer is included in a modeling material thatis devoid of one or more of the components which are activatable byexposure to radiation. Such components include, for example, an activeROMP catalyst that is encapsulated by a photodegradable capsule, alatent ROMP catalyst that is photoactivatable, a latent activator thatis photoactivatable, an activator that is encapsulated by aphotodegradable capsule, a photoinitiator, as described herein, aninitiator or co-initiator that in encapsulated in photodegradablecapsule, and so forth.

Exemplary photosensitizers include, but are not limited to,2-isopropylthioxanthone and 4-isopropylthioxanthone, marketed asSPEEDCURE ITX and referred to herein also as ITX, 9,10-Dibutoxyanthracene marketed as Anthracure® UVS-1331, Phenothiazine (253 and 318nm), Anthracene, and a curcumin compound such as marketed as Ecocolcurcumin colour 95%.

Table 2 below presents a list of exemplary components which can beincluded, in any combination, in a UV-curable non-ROMP system asdescribed herein in any one of the embodiments and any combinationsthereof. In embodiments pertaining to a dual jetting methodology, thecomponents can be included in one or more modeling materialformulations, as described herein.

TABLE 2 Trade Name Chemical Type Function Supplier SR423A Isobornylmethacrylate Free radical Sartomer Oligomer SR-843 Tricyclodecanedimethanol Free radical Sartomer dimethacrylate Monomer SR-351Trimethylol propane triacrylate Free radical Sartomer bifunctionalmonomer (Cross- linker) PHOTOMER 4028F Bis Phenol A Ethoxylated Freeradical Cognis Diacrylate Acrylic oligomer (bifunctional) SR506DIsobornyl acrylate Free radical Sartomer Acrylic oligomer SR833STricyclodecane dimethanol Free radical Sartomer diacrylate Acrylicoligomer EBECRYL 350 Silicon acrylated oligomer Phase separation UCBpromoter Chemicals UVCURE 1600 P-(octyloxyphenyl)phenyl- Cationic CYTECiodonium photoinitiator hexafluoroantimonate IGRACURE I-651 Alpha,alpha-dimethoxy alpha Free radical CIBA phenylacetophenonephotoinitiator Uvacure 1500 Cycloaliphatic epoxide Cationic monomerCytec TPO Diphenyl (2,4,6 trimethylbenzoyl) Free radical BASF phosphineoxide photoinitiator BR 970 Urethane diacrylate Free radical IGM Acrylicoligomer SPEEDCURE IX 2-isopropylthioxanthone and 4- Cationic LAMBSONisopropylthioxanthone photosensitizer BYK 3570 Acrylfunctional polyesterAdditive BYK modified polydimethlsiloxane CURCUMIN1,6-Heptadiene-3,5-dione, 1,7- Cationic AXOWINbis(4-hydroxy-3-methoxyphenyl)- photosensitizer DBS-C21 Carbinolhydroxyterminated Toughening agent GELEST PDMS

Toughening Agents:

According to embodiments of the present invention, in each of themethodologies described herein, one or more of the modeling materialformulations further comprises a toughening agent.

As demonstrated and discussed in Example 3 hereinbelow, the presentinventors have shown that the addition of a toughening agent providesfor substantially improved mechanical properties. The present inventorshave further identified some characteristics of a toughening agent,which result in enhanced improvement in the mechanical properties andimproved suitability to 3D inkjet printing.

The toughening agent, according to the present embodiments, can be addedto the modeling material formulation in case of “single jetting”methodologies, as described herein in any of the respective embodiments.

The toughening agent, according to the present embodiments, can be addedto one or more (e.g., two) of the modeling material formulations in caseof “multi (e.g., dual) jetting” methodologies, as described herein inany of the respective embodiments.

The phrase “toughening agent” is also referred to herein as a “toughnessmodifying agent” or “toughness modifier” and encompasses one or more(e.g., a mixture of two or more) toughening agents and is used herein todescribe agents that modify (e.g., improve) the toughness of a materialcontaining same.

In some embodiments, the toughness is reflected by Impact resistanceand/or tensile strength.

In some embodiments, a toughness modifying agent (a toughening agent)improves the Impact resistance and/or Tensile strength of a materialcontaining same. In some embodiments, a toughness modifying agent (atoughening agent) improves the Impact resistance of a materialcontaining. In some embodiments, a toughness modifying agent (atoughening agent) improves the Tensile strength of a material containingsame. In some embodiments, a toughness modifying agent (a tougheningagent) improves the Impact resistance and the Tensile strength of amaterial containing same.

The phrase “toughening agent” encompasses materials referred to hereinas “Impact modifying agents” or “Impact modifiers”.

According to some of any of the embodiments of the present invention,the toughening agent (e.g., Impact modifying agent) is an elastomericmaterial.

The phrase “elastomeric material” is also referred to herein and in theart interchangeably as “elastomer” and encompasses deformable,viscoelastic polymeric materials (typically co-polymers), includingrubbers, liquid rubbers and rubbery-like materials. In some embodiments,an elastomeric material as described herein comprises saturated and/orunsaturated hydrocarbon chains, preferably long hydrocarbon chains of atleast 20 carbon atoms in length. In some embodiments, the hydrocarbonchains do not include heteroatoms (e.g., oxygen, nitrogen, sulfur)interrupting the chain or forming a part of the substituents of thechain.

In some embodiments, by “hydrocarbon” it is meant herein a materialcontaining one or more chains comprised mainly (e.g., 80%, or 85% or90%, or 95%, or 100%) of carbon and hydrogen atoms, linked to oneanother. Exemplary hydrocarbons include one or more alkyl, cycloalkyland/or aryl moieties covalently linked to one another at any order.

Non-limiting examples of toughening agents include elastomeric materialssuch as, but not limited to, natural rubber, butyl rubber, polyisoprene,polybutadiene, polyisobutylene, ethylene-propylene copolymer (EPR),styrene-butadiene-styrene triblock rubber, random styrene-butadienerubber, styrene-isoprene-styrene triblock rubber,styrene-ethylene/butylene-styrene copolymer,styrene-ethylene/propylene-styrene copolymer, andethylene-propylene-diene terpolymers.

According to some of any of the embodiments described herein, theelastomeric material is characterized by at least one, at least two, orall of the following:

featuring a molecular weight lower than 50,000, or lower than 40,000,or, preferably, lower than 30,000, or lower than 20,000, or lower than10,000 Daltons;

being non-reactive towards ROMP;

being dissolvable or dispersible in the one or more modeling materialformulation(s) comprising same; and

being capable of forming a multiphase (e.g., biphasic) structure whenblended with the cured modeling material.

According to some of any of the embodiments described herein, theelastomeric material is dissolvable or dispersible in the modelingmaterial formulation comprising same.

Depending on the methodology, the modeling material formulationcomprising the elastomeric material may comprise a ROMP monomer and/or anon-ROMP monomer.

ROMP monomers and formulations containing same are typicallyhydrophobic. Therefore, in some embodiments, the elastomeric material isselected as dissolvable or dispersible in a modeling materialformulation which comprises a ROMP monomer. In some embodiments, theelastomeric material is hydrophobic, and thereby exhibits compatibility,and dissolvability or dispersibility in the ROMP monomer formulation,which has a hydrophobic nature. In other embodiments, the elastomericmaterial is selected dissolvable or dispersible in a formulation whichcomprises, in addition to, or instead of, the ROMP monomer, a non-ROMPcurable material as described herein in any of the respectiveembodiments.

According to some of any of the embodiments described herein, theelastomeric material is selected capable of forming a multiphase (e.g.,biphasic) structure when blended with the cured modeling material.

As explained in Example 3 hereinbelow and as known in the art, Impactresistance can be improved in case of a phase separation between theimpact modifying agent and the polymeric matrix with which it isblended, namely, in a case where there is a biphasic or multiphasicstructure of the blend.

In some embodiments, an elastomeric material that is capable of forminga multiphase (e.g., biphasic) structure when blended with said curedmodeling material can be regarded as non-soluble in the polymeric matrixformed upon exposing the modeling material formulation(s) to curingcondition, namely, in the cured (or partially cured) modeling material.

According to some of any of the embodiments described herein, theelastomeric material is selected such that it is dissolvable ordispersible in the modeling material comprising same, and is furthercapable of forming a multiphase (e.g., biphasic) structure when blendedwith the cured modeling material.

In some of the embodiments pertaining to an elastomeric material that iscapable of forming a multiphasic structure when blended with the curedmodeling material, the ROMP monomer is or comprises a DCPD or aderivative thereof, as described herein.

It is to be noted that phase separation is not required for an Impactmodifying agent to provide its effect in all cases. That is, when anelastomeric material is blended with a cured modeling material formed ofa ROMP monomer-containing modeling material formulation(s), Impactresistance can be improved also when there is no phase separation (nobiphasic or multiphasic structure is formed).

According to some of any of the embodiments described herein, theelastomeric material is non-reactive towards ROMP. By “non-reactivetowards ROMP” it is meant that the elastomeric material does featurefunctional groups that can participate in ROMP. As known in the art,ROMP involves materials featuring unsaturated bonds. Accordingly,exemplary elastomeric materials which are non-reactive towards ROMP aresaturated polymeric materials, namely, polymers and/or copolymers whichdo not comprise unsaturated bonds in their backbone chain. The pendantgroups of such elastomeric materials may or may not comprise unsaturatedbonds.

Elastomeric materials featuring a saturated backbone chain, namely, aredevoid of unsaturated bonds in their backbone chain, are defined hereinas “saturated” elastomeric materials.

In some of the embodiments pertaining to an elastomeric material that isnon-reactive towards ROMP, the ROMP monomer is or comprises a DCPD or aderivative thereof, as described herein.

According to some embodiments of the present invention, the elastomericmaterial is a low molecular weight material, as defined herein, which isa saturated polymer or co-polymer.

According to some embodiments of the present invention, the elastomericmaterial is a low molecular weight material, as defined herein, which ishydrophobic.

According to some embodiments of the present invention, the elastomericmaterial is a low molecular weight material, as defined herein, which isa saturated polymer or co-polymer and which is further characterized ashydrophobic.

According to some of these embodiments, the elastomeric material isfurther characterized as dissolvable or dispersible in the modelingmaterial formulation containing same and optionally further as forming abiphasic structure with the cured modeling material.

Non-limiting examples of elastomers usable as toughening agentsaccording to the present embodiments include low molecular weight EPRelastomers, and low molecular weight polybutenes. Exemplary elastomericmaterials suitable for use according to some of the present embodimentsinclude, but are not limited to, low MW EPDM such as Trilene 67(MW=37,000 Da) or Trilene 77 (MW=27,000 Da), liquid EPR elastomers suchas Trilene CP80 (MW=23,000 Da) or Trilene CP1100 (MW=6600 Da), low MWpolybutenes, low MW polyisoprenes, and the like. Preferred exemplaryelastomeric materials include, but are not limited to, liquid EPRelastomers and polybutenes, having MW lower than 20,000 or lower than12,000 Daltons.

Non-limiting examples of such elastomers are presented in Table 15hereinbelow.

According to some of any of the embodiments, a concentration of thetoughening agent (e.g., an elastomeric material as described herein) mayrange from about 0.1% to about 20%, or from about 1 to about 20%, orfrom about 1 to about 15%, or from about 1 to about 12%, or from about 1to about 10%, or from about 2 to about 10%, or from about 2 to about 8%,by weight, of the total weight of a formulation containing same,including any intermediate values and subranges therebetween.

A concentration of the toughening agent (e.g. elastomeric materials asdescribed herein), may range from about 0.10 phr to about 10 phr, orfrom about 0.1 phr to about 5 phr, relative to the weight of theformulation containing same.

A concentration of the toughening agent (e.g. elastomeric material asdescribed herein) may alternatively range from about 0.1% to about 20%,or from about 1% to about 20%, or from about 1% to about 20%, or fromabout 5% to about 15% or from about 5% to about 10%, by weight, of thetotal weight of a formulation containing same, including anyintermediate values and subranges therebetween.

In some embodiments, each of the modeling material formulationscomprises an elastomeric material, as described herein.

Additional Materials:

In some of any of the embodiments described herein, a modeling materialformulation can further comprise one or more additional materials, whichare referred to herein also as non-reactive materials.

Such agents include, for example, surface active agents, stabilizers,antioxidants, fillers, pigments, and/or dispersants.

In cases of multi-jetting methodologies, the non-reactive agents can beindependently included in one or all of the modeling materialformulations.

The term “filler” describes an inert material that modifies theproperties of a polymeric material and/or adjusts a quality of the endproducts. The filler may be an inorganic particle, for example calciumcarbonate, silica, and clay.

Fillers may be added to the modeling formulation in order to reduceshrinkage during polymerization or during cooling, for example, toreduce the coefficient of thermal expansion, increase strength, increasethermal stability, reduce cost and/or adopt rheological properties.Nanoparticles fillers are typically useful in applications requiring lowviscosity such as ink jet applications.

In some embodiments, a modeling formulation comprises a surface activeagent. A surface-active agent may be used to reduce the surface tensionof the formulation to the value required for jetting or for printingprocess, which is typically from about 10 to about 50 dyne/cm. Anexemplary such agent is a silicone surface additive.

Suitable stabilizers (stabilizing agents) include, for example, thermalstabilizers, which stabilize the formulation at high temperatures.

In some embodiments, the modeling formulation comprises one or morepigments. In some embodiments, the pigment's concentration is lower than35%, or lower than 25% or lower than 15%, by weight.

The pigment may be a white pigment. The pigment may be an organicpigment or an inorganic pigment, or a metal pigment or a combinationthereof.

In some embodiments the modeling formulation further comprises a dye.

In some embodiments, combinations of white pigments and dyes are used toprepare colored cured materials.

The dye may be any of a broad class of solvent soluble dyes. Somenon-limiting examples are azo dyes which are yellow, orange, brown andred; anthraquinone and triarylmethane dyes which are green and blue; andazine dye which is black.

In some of any of the embodiments described herein, one or more of themodeling material formulations comprises one or more toughening agent(s)and/or impact modifying agent(s), in addition to the elastomericmaterials described herein as preferred toughening agents.

These may include, as non-limiting examples, carbon fibers, carbonnanotubes, glass fibers, aramid Keylar, polyparaphenylenebenzobisoxazole Zylon, and other polar and non polar impact modifiers.

Alternatively, or in addition, elastomeric materials other than theelastomeric materials described herein can be included. In someembodiments, a concentration of such elastomeric materials, if present,is lower than a concentration of the elastomeric materials describedherein.

In some embodiments, one or more of the modeling material formulationscomprises an antioxidant. In some embodiments, at least a modelingmaterial formulation that comprises a ROMP catalyst comprises anantioxidant.

In some embodiments, one or more, or each, of the modeling materialformulations comprises a proton donor. Proton donors are useful foraccelerating the activation of a pre-catalyst by the activator, tothereby accelerate the ROMP reaction, in case such a catalyst is used.For example, a proton donor, when contacted with a chlorosilaneactivator as described herein generates HCl, which accelerates theactivation of the pre-catalyst.

The proton donors can be reactive (curable) or non-reactive. Curableproton donors include, for example, ROMP monomers which bear acidicprotons (e.g., hydroxy groups).

An exemplary proton donor is a hydroxy alkyl, for example, 1-butanol.

A concentration of the proton donor can range from about 0.1 to about2%, by weight, of a modeling material formulation containing same,including any intermediate values and subranges therebetween.

Kits:

According to some of any of the embodiments described herein, there areprovided kits containing modeling material formulations as describedherein.

In some embodiments, a kit comprises a modeling material formulation foruse in a single jetting and single curing methodology, as describedherein. The components of the modeling material formulations arepackaged together in the kit and include a ROMP monomer or monomers, asdescribed in any of the respective embodiments, a ROMP catalyst, whichcan be active or latent, or can be a system of a pre-catalyst and anactivator (latent or active).

In some embodiments, and in accordance with any of the respectiveembodiments described herein for single jetting and single curingapproach, one or more of the components in the kit can be physicallyseparated from the other components (e.g., encapsulated, as describedherein).

In some embodiments, a kit comprises a modeling material formulation foruse in a single jetting and dual or multi-curing methodology, asdescribed herein. The components of the modeling material formulationsare packaged together in the kit and include a ROMP monomer or monomers,as described in any of the respective embodiments, a ROMP catalyst,which can be active or latent, or can be a system of a pre-catalyst andan activator (latent or active), and components of an additional curablesystem, as described herein in any of the respective embodiments.

In some embodiments, and in accordance with any of the respectiveembodiments described herein for single jetting and dual or multi-curingapproach, one or more of the components in the kit can be physicallyseparated from the other components (e.g., encapsulated, as describedherein).

In some embodiments, a kit comprises a modeling material formulation foruse in a dual or multi jetting and single curing methodology, asdescribed herein. The components of each of the modeling materialformulations are packaged individually in the kit and include a ROMPmonomer or monomers, as described in any of the respective embodiments,a ROMP catalyst, which can be active or latent, or can be a system of apre-catalyst and an activator (latent or active), divided in theformulations in accordance with any one of the respective embodiments.

In some embodiments, and in accordance with any of the respectiveembodiments described herein for dual or multi jetting and single curingapproach, one or more of the components in one or more formulations canbe physically separated from the other components (e.g., encapsulated,as described herein) in a respective formulation.

In some embodiments, a kit comprises a modeling material formulation foruse in a dual or multi jetting and dual or multi-curing methodology, asdescribed herein. The components of each of the modeling materialformulations are packaged individually in the kit and include a ROMPmonomer or monomers, as described in any of the respective embodiments,a ROMP catalyst, which can be active or latent, or can be a system of apre-catalyst and an activator (latent or active), and components of oneor more additional curable systems, as described herein in any of therespective embodiments.

In some embodiments, and in accordance with any of the respectiveembodiments described herein for dual or multi jetting dual ormulti-curing approach, one or more of the components in one or moreformulations can be physically separated from the other components(e.g., encapsulated, as described herein) in a respective formulation.

In some of any of the embodiments described herein for a kit, one ormore (if present) modeling material formulation(s) further comprise(s) atoughening agent (e.g., an elastomeric material) as described herein inany of the respective embodiments.

In some embodiments, the kit further comprises one or more tougheningagents (e.g., elastomeric materials as described herein) which arepackaged separately from the one or more modeling material formulations,and in some embodiments, the kit further comprises instructions to addthe toughening agent(s) to one or more modeling material formulationsprior to use.

In exemplary embodiments, the one or more modeling material formulationsas described herein is/are packaged in a suitable packaging material,preferably, an impermeable material (e.g., water- and gas-impermeablematerial), and further preferably an opaque material. In someembodiments, the kit further comprises instructions to use theformulations in an additive manufacturing process, preferably a 3Dinkjet printing process as described herein. The kit may furthercomprise instructions to use the formulations in the process inaccordance with the method as described herein. Alternatively, or inaddition, the kit may further comprise instructions to use theformulations in molding, for example, for preparing molds that areusable in additive manufacturing and/or in reactive injection moldingprocesses as described herein in any of the respective embodiments.

In some embodiments, pertaining to a dual jetting approach, the kitsinclude two or more modeling material formulations individually packagedin the kit. In some of these embodiments, the kit further comprisesinstructions to avoid contact between the first and second formulationsat any stage before printing is effected (e.g., before the formulationsare dispensed from the nozzles).

In some embodiments the kit comprises two or more modeling materialformulations, at least one of the formulations comprises a ROMP monomeras described herein in any of the respective embodiments, at least oneof the formulations comprises a ROMP pre-catalyst, as described hereinin any of the respective embodiments, and at least one of theformulations comprises a ROMP activator as described herein in any ofthe respective embodiments, wherein the ROMP activator and the ROMPpre-catalyst are not in the same formulation. In some of theseembodiments, one or both formulations further comprises a tougheningagent as described herein in any of the respective embodiments.

In some of these embodiments, a first modeling material formulation(also referred to herein as Part A) comprises a ROMP monomer asdescribed herein (e.g., a RIM monomer), and a pre-catalyst as describedherein (e.g., a mixture of two pre-catalysts as described herein).

In some of these embodiments, the first formulation further comprises atoughening agent as described herein, and a ROMP inhibitor, as describedherein, and optionally further comprises an antioxidant and/or a protondonor. In some of these embodiments, the toughening agent is anelastomer or an elastomeric material, as described herein in any of therespective embodiments.

In exemplary embodiments, the first formulation comprises a ROMP monomeras described herein (e.g., a RIM monomer), at a concentration of from 50to 99% or from 70 to 99%, by weight, and a pre-catalyst as describedherein (e.g., a mixture of two pre-catalysts as described herein), at aconcentration of from 0.01 to 0.1% by weight, and optionally furthercomprises a ROMP inhibitor as described herein, at a concentration of 1to 200 ppm, or 1 to 60 ppm, as described herein, a toughening agent(e.g., an elastomeric material as described herein) at a concentrationof from 0.1 to 20%, by weight, and/or an anti-oxidant, at aconcentration of 0.01-5%, by weight, and/or a filler as describedherein, at a concentration of 0.01-20% by weight, of the total weight ofthe formulation.

In some of any of these embodiments, a second modeling materialformulation (also referred to herein as Part B) comprises a ROMP monomeras described herein (e.g., a RIM monomer), which can be the same ordifferent from the ROMP monomer included in the first formulation, and aROMP activator (e.g., an organic chlorosilane), as described herein inany of the respective embodiments.

In some of these embodiments, the second formulation further comprises atoughening agent as described herein. In some of these embodiments, thetoughening agent is an elastomer or an elastomeric material, asdescribed herein in any of the respective embodiments.

In exemplary embodiments, the second formulation comprises a ROMPmonomer as described herein (e.g., a RIM monomer), at a concentration offrom 50 to 99% or from 70 to 99%, by weight, and a ROMP activator asdescribed herein (e.g., an organic chlorosilane), at a concentration offrom 0.01 to 2% by weight, and optionally further comprises a tougheningagent (e.g., an elastomeric material as described herein) at aconcentration of from 0.1 to 20%, by weight, and/or a filler asdescribed herein, at a concentration of 0.01-20% by weight, of the totalweight of the formulation.

In some of any of these embodiments, the first formulation is devoid ofan activator.

In some of any of these embodiments, the second formulation is devoid ofa pre-catalyst.

The Object:

According to an aspect of some embodiments of the present inventionthere is provided a three-dimensional object which comprises a polymericmaterial obtainable by ROMP of respective ROMP monomer or combination ofROMP monomers. In some embodiments, the 3D object further comprises, inat least a part thereof, a toughening agent (e.g., an Impact modifyingagent, an elastomeric material) as described herein in any of therespective embodiments.

In some embodiments, the 3D object further comprises, in at least a partthereof, a material featuring antioxidation, for example, in a form of alayer deposited on the surface of the object or a part thereof asdescribed herein.

In some of these embodiments, the 3D object is obtainable by 3D inkjetprinting.

According to an aspect of some embodiments of the present inventionthere is provided a three-dimensional object fabricated by a 3D inkjetprinting process, which is characterized by an impact resistance of atleast 80 J/m.

In some embodiments, the object is characterized by an impact resistanceof at least 100, at least 150, at least 180, at least 200 J/m, and evenhigher impact resistance

Herein throughout and in the art, the phrase “Impact resistance”, whichis also referred to interchangeably, herein and in the art, as “Impactstrength” or simply as “impact”, describes the resistance of a materialto fracture by a mechanical impact, and is expressed in terms of theamount of energy absorbed by the material before complete fracture.Impact resistance can be measured using, for example, the ASTM D256-06standard Izod impact testing (also known as “Izod notched impact”, or as“Izod impact”), and/or as described hereinunder, and is expressed asJ/m.

In some embodiments, the object is characterized by heat deflectiontemperature (HDT) which is at least 50, at least 60, at least 60, atleast 70, at least 80, at least 90, at least 100, at least 110 an evenat least 120° C.

Herein throughout and in the art, the phrase “heat deflectiontemperature”, or HDT, describes the temperature at which a specimen ofcured material deforms under a specified load. Determination of HDT canbe performed using the procedure outlined in ASTM D648-06/D648-07 and/oras described hereinunder.

The fabrication of 3D objects by a 3D inkjet printing process is enabledby the use of ROMP systems, as described herein.

In some embodiments, the 3D object further comprises, in at least a partthereof, a material featuring antioxidation, for example, in a form of alayer deposited on the surface of the object or a part thereof asdescribed herein.

Molds:

According to some of any of the embodiments described herein, a methodof fabricating a 3D object as described herein in any of the respectiveembodiments can be utilized for preparing a 3D-printed (e.g., 3D-inkjetprinted) mold.

A mold as described herein can be used, for example, in reactiveinjection molding, or in any other molding techniques used forfabricating three-dimensional objects.

According to an aspect of some embodiments of the present inventionthere is provided a method of fabricating a three-dimensional object,the method comprising: sequentially forming a plurality of layers in aconfigured pattern corresponding to a shape of a mold (e.g., having aninner surface shaped in accordance with an outer surface of thethree-dimensional object); and

introducing into the mold a molding composition which comprises anunsaturated cyclic monomer polymerizable by ROMP, a catalyst forinitiating ROMP of the monomer and a toughening agent (e.g., an impactmodifying agent) as described herein, thereby fabricating thethree-dimensional object.

In some of these embodiments, the molding composition comprises a ROMPsystem as described in any of the respective embodiments describedherein for single jetting single curing, excluding embodiments in whichone or more of the components is physically separated in theformulation.

In some embodiment, the method further comprises exposing the mold to acondition for inducing initiation of ROMP of the monomer by thecatalyst. Such a condition can include a condition for activating alatent catalyst, or a condition for activating a latent activator, orany other condition for promoting the ROMP.

In some embodiments, the formation of each of the layers forming themold comprises dispensing by at least one inkjet printing head at leastone modeling material formulation.

In some of these embodiments, the modeling material formulation(s)comprise a non-ROMP curable system as described herein in any of therespective embodiments. In some embodiments, the non-ROMP curable systemis a UV-curable non-ROMP system, as described herein in any of therespective embodiments.

The Printing System:

FIG. 2 is a schematic illustration of a system 110 suitable for 3Dinkjet printing of an object 112 according to some embodiments of thepresent invention. System 110 comprises a printing apparatus 114 havinga printing unit 116 which comprises a plurality of printing heads. Eachhead preferably comprises an array of one or more nozzles 122, asillustrated in FIGS. 3A-3C described below, through which a liquid(uncured) building material 124 is dispensed. Preferably, apparatus 114is a three-dimensional inkjet printing apparatus. FIGS. 3A-3B illustratea printing head 116 with one (FIG. 3A) and two (FIG. 3B) nozzle arrays22. The nozzles in the array are preferably aligned linearly, along astraight line. In embodiments in which a particular printing head hastwo or more linear nozzle arrays, the nozzle arrays are optionally andpreferably can be parallel to each other. In some embodiments, two ormore printing heads can be assembled to a block of printing heads, inwhich case the printing heads of the block are typically parallel toeach other. A block including several inkjet printing heads 116 a, 116b, 116 c is illustrated in FIG. 3C. Printing heads 116 are optionallyand preferably oriented along the indexing direction with theirpositions along the scanning direction being offset to one another.

Each printing head is optionally and preferably fed via a buildingmaterial reservoir which may optionally include a temperature controlunit (e.g., a temperature sensor and/or a heating device), and amaterial level sensor. To dispense the building material, a voltagesignal is applied to the printing heads to selectively deposit dropletsof material via the printing head nozzles, for example, as inpiezoelectric inkjet printing technology. The dispensing rate of eachhead depends on the number of nozzles, the type of nozzles and theapplied voltage signal rate (frequency). Such printing heads are knownto those skilled in the art of solid freeform fabrication.

Preferably, but not obligatorily, the overall number of printing nozzlesor nozzle arrays is selected such that half of the printing nozzles aredesignated to dispense support material formulation(s) and half of theprinting nozzles are designated to dispense modeling materialformulation(s), i.e. the number of nozzles jetting modeling materialformulations is the same as the number of nozzles jetting supportmaterial formulations. In the representative example of FIG. 2 , fourprinting heads 116 a, 116 b, 116 c and 116 d are illustrated. Each ofheads 116 a, 116 b, 116 c and 116 d has a nozzle array. In this Example,heads 116 a and 116 b can be designated for modeling material/s andheads 116 c and 116 d can be designated for support material. Thus, head116 a can dispense a first modeling material formulation, head 116 b candispense a second modeling material formulation and heads 116 c and 116d can both dispense a support material formulation. In an alternativeembodiment, heads 116 c and 116 d, for example, may be combined in asingle head having two nozzle arrays for depositing a support materialformulation.

Yet it is to be understood that it is not intended to limit the scope ofthe present invention and that the number of modeling materialformulations depositing heads (modeling heads) and the number of supportmaterial depositing heads (support heads) may differ. Generally, thenumber of modeling heads, the number of support heads and the number ofnozzles in each respective head or head array are selected such as toprovide a predetermined ratio, a, between the maximal dispensing rate ofthe support material and the maximal dispensing rate of modelingmaterial. The value of the predetermined ratio, a, is preferablyselected to ensure that in each formed layer, the height of modelingmaterial equals the height of support material. Typical values for a arefrom about 0.6 to about 1.5.

For example, for a=1, the overall dispensing rate of support material isgenerally the same as the overall dispensing rate of the modelingmaterial when all modeling heads and support heads operate.

In a preferred embodiment, there are M modeling heads each having marrays of p nozzles, and S support heads each having s arrays of qnozzles such that M×m×p=S×s×q. Each of the M×m modeling arrays and S×ssupport arrays can be manufactured as a separate physical unit, whichcan be assembled and disassembled from the group of arrays. In thisembodiment, each such array optionally and preferably comprises atemperature control unit and a material level sensor of its own, andreceives an individually controlled voltage for its operation.

Apparatus 114 can further comprise a hardening device 324 which caninclude any device configured to emit light, heat or any other curingenergy that may cause the deposited material to harden. For example,hardening device 324 can comprise one or more radiation sources, whichcan be, for example, an infrared lamp or any other source emittingheat-inducing radiation, as further detailed hereinabove, a UV radiationsource. In some embodiments of the present invention, hardening device324 serves for applying a curing condition to the modeling material.

The printing head and radiation source are preferably mounted in a frameor block 128 which is preferably operative to reciprocally move over atray 360, which serves as the working surface. Apparatus 114 can furthercomprise a tray heater 328 configured for heating the tray. Theseembodiments are particularly useful when the modeling material ishardened by heating (exposure to heat).

In some embodiments of the present invention the radiation sources aremounted in the block such that they follow in the wake of the printingheads to at least partially cure or solidify the materials justdispensed by the printing heads. Tray 360 is positioned horizontally.According to the common conventions an X-Y-Z Cartesian coordinate systemis selected such that the X-Y plane is parallel to tray 360. Tray 360 ispreferably configured to move vertically (along the Z direction),typically downward.

In various exemplary embodiments of the invention, apparatus 114 furthercomprises one or more leveling devices 132. Leveling device 132 servesto straighten, level and/or establish a thickness of the newly formedlayer prior to the formation of the successive layer thereon. Levelingdevice 132 can comprise one or more rollers 326. Rollers 326 can have agenerally smooth surface or can have a patterned surface. In someembodiments of the present invention one or more of the layers isstraightened while the formulation within the layer is at a cured orpartially cured state. In these embodiments, leveling device 132 iscapable of reforming the solidified portion of the formulation. Forexample, when leveling device 132 comprises one or more rollers at leastone of these rollers is capable of milling, grinding and/or flaking thesolidified portion of the formulation. Preferably, in these embodiments,the roller has a non-smooth surface so as to facilitate the milling,grinding and/or flaking. For example, the surface of the roller can bepatterned with blades and/or have a shape of an auger.

In some embodiments of the present invention one or more of the layersis straightened while the formulation within the layer is uncured. Inthese embodiments, leveling device 132 can comprise a roller or a blade,which is optionally and preferably, but not necessarily, incapable ofeffecting milling, grinding and/or flaking.

Leveling device 132 preferably comprises a waste collection device 136for collecting the excess material generated during leveling. Wastecollection device 136 may comprise any mechanism that delivers thematerial to a waste tank or waste cartridge. Optionally, leveling device132 is a self-cleaning leveling device, wherein cured or partially curedformulation is periodically removed from leveling device 132. Arepresentative Example of a self-cleaning leveling device is illustratedin FIG. 4 . Shown in FIG. 4 is a double roller having a first roller 356that contacts and straightens a layer 358 and a second roller 354 thatis in contact with the first roller 356 but not with the layer 358 andwhich is configured to remove the formulation from the first roller 358.When first roller 356 has a non-smooth surface, second roller 354preferably is also non-smoothed wherein the pattern formed on thesurface of roller 354 is complementary to the pattern formed on thesurface of roller 356, so as to allow roller 354 to clean the surface ofroller 358.

Apparatus 114 can also comprise a chamber 350 enclosing at least heads116 and tray 360, but may also enclose other components of system 110,such as, but not limited to, devices 132 and 324, frame 128 and thelike. In some embodiments of the present invention apparatus 114comprises a chamber heater 352 that heats the interior of chamber 350 asfurther detailed hereinabove. Chamber 350 is preferably generally sealedto an environment outside chamber 350.

In some embodiments of the present invention chamber 350 comprises a gasinlet 364 and the system comprises a gas source 366 configured forfilling said chamber by an inert gas through gas inlet 364. Gas source366 can be a container filled with the inert gas. The gas can be any ofthe inert gases described above. Optionally, chamber 350 is also formedwith a gas outlet 368 for allowing the gas to exit chamber 350 ifdesired. Both inlet 366 and outlet 368 are of the present embodimentsprovided with valves (not shown) so as to controllably allow entryand/or exit of the gas to and from chamber 350. Preferably, controller152 generates, continuously or intermittently, inflow and outflow of theinert gas through gas inlet 366 and gas outlet 368. This can be achievedby configuring controller 152 to control at least one of source 366,inlet 364 and outlet 368. Optionally, system 110 comprises a gas flowgenerating device 370, placed within chamber 350 and configured forgenerating a flow of the inert gas within chamber 350. Device 370 can bea fan or a blower. Controller 152 can be configured for controlling alsodevice 370, for example, based on a predetermined printing protocol.

In some embodiments of the present invention apparatus 114 comprises amixing chamber 362 for preparing the modeling material formulation priorto entry of the modeling material formulation into a respective head. Inthe schematic illustration of FIG. 2 , which is not to be considered aslimiting, chamber 362 receives materials from different containers,mixes the received materials and introduces the mix to two heads (heads116 b and 116 a, in the present example). However, this need notnecessarily be the case since in some embodiments chamber 362 canreceive materials from different containers, mixes the receivedmaterials and introduces the mix only to more than two heads of only toone head. Preferably, the position and fluid communication betweenmixing chamber 362 and respective head is selected such that at least80% or at least 85% or at least 90% or at least 95% or at least 99% orthe modeling material formulation that enters the respective head orheads (e.g., heads 116 b and 116 a in the present example) remainsuncured. For example, chamber 362 can be attached directly to theprinting head or the printing block, such that motion of the printinghead is accompanied by motion of the mixing chamber. These embodimentsare particularly useful when the formulation undergoes fastpolymerization reaction even in the absence of curing radiation.

In use, the dispensing heads of unit 116 move in a scanning direction,which is referred to herein as the X direction, and selectively dispensebuilding material in a predetermined configuration in the course oftheir passage over tray 360. The building material typically comprisesone or more types of support material and one or more types of modelingmaterial. The passage of the dispensing heads of unit 116 is followed bythe curing of the modeling material(s) by radiation source 126. In thereverse passage of the heads, back to their starting point for the layerjust deposited, an additional dispensing of building material may becarried out, according to predetermined configuration. In the forwardand/or reverse passages of the dispensing heads, the layer thus formedmay be straightened by leveling device 326, which preferably follows thepath of the dispensing heads in their forward and/or reverse movement.Once the dispensing heads return to their starting point along the Xdirection, they may move to another position along an indexingdirection, referred to herein as the Y direction, and continue to buildthe same layer by reciprocal movement along the X direction.Alternately, the dispensing heads may move in the Y direction betweenforward and reverse movements or after more than one forward-reversemovement. The series of scans performed by the dispensing heads tocomplete a single layer is referred to herein as a single scan cycle.

Once the layer is completed, tray 360 is lowered in the Z direction to apredetermined Z level, according to the desired thickness of the layersubsequently to be printed. The procedure is repeated to formthree-dimensional object 112 in a layerwise manner.

In another embodiment, tray 360 may be displaced in the Z directionbetween forward and reverse passages of the dispensing head of unit 116,within the layer. Such Z displacement is carried out in order to causecontact of the leveling device with the surface in one direction andprevent contact in the other direction.

System 110 optionally and preferably comprises a building materialsupply system 330 which comprises the building material containers orcartridges and supplies a plurality of building materials to fabricationapparatus 114.

A control unit 340 controls fabrication apparatus 114 and optionally andpreferably also supply system 330. Control unit 340 typically includesan electronic circuit configured to perform the controlling operations.Control unit 340 preferably communicates with a data processor 154 whichtransmits digital data pertaining to fabrication instructions based oncomputer object data, e.g., a CAD configuration represented on acomputer readable medium in a form of, for example, a StandardTessellation Language (STL) format Standard Tessellation Language (STL),StereoLithography Contour (SLC) format, Virtual Reality ModelingLanguage (VRML), Additive Manufacturing File (AMF) format, DrawingExchange Format (DXF), Polygon File Format (PLY) or any other formatsuitable for CAD. Typically, control unit 340 controls the voltageapplied to each printing head or nozzle array and the temperature of thebuilding material in the respective printing head.

Once the manufacturing data is loaded to control unit 340 it can operatewithout user intervention. In some embodiments, control unit 340receives additional input from the operator, e.g., using data processor154 or using a user interface 118 communicating with unit 340. Userinterface 118 can be of any type known in the art, such as, but notlimited to, a keyboard, a touch screen and the like. For example,control unit 340 can receive, as additional input, one or more buildingmaterial types and/or attributes, such as, but not limited to, color,characteristic distortion and/or transition temperature, viscosity,electrical property, magnetic property. Other attributes and groups ofattributes are also contemplated.

It is expected that during the life of a patent maturing from thisapplication many relevant components of a ROMP system as describedherein will be developed and the scope of the terms ROMP monomer, ROMPcatalyst, ROMP activator, ROMP pre-catalyst, is intended to include allsuch new technologies a priori.

It is expected that during the life of a patent maturing from thisapplication many relevant degradable capsules and other technologies forphysically separating components in a modeling material formulation asdescribed herein will be developed and the scope of the terms physicalseparation and degradable capsule, is intended to include all such newtechnologies a priori.

As used herein the term “about” refers to ±10% or ±5%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

As used herein the term “method” refers to manners, means, techniquesand procedures for accomplishing a given task including, but not limitedto, those manners, means, techniques and procedures either known to, orreadily developed from known manners, means, techniques and proceduresby practitioners of the chemical, pharmacological, biological,biochemical and medical arts.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Herein throughout, the phrase “linking moiety” or “linking group”describes a group that connects two or more moieties or groups in acompound. A linking moiety is typically derived from a bi- ortri-functional compound, and can be regarded as a bi- or tri-radicalmoiety, which is connected to two or three other moieties, via two orthree atoms thereof, respectively.

Exemplary linking moieties include a hydrocarbon moiety or chain,optionally interrupted by one or more heteroatoms, as defined herein,and/or any of the chemical groups listed below, when defined as linkinggroups.

When a chemical group is referred to herein as “end group” it is to beinterpreted as a substituent, which is connected to another group viaone atom thereof.

Herein throughout, the term “hydrocarbon” collectively describes achemical group composed mainly of carbon and hydrogen atoms. Ahydrocarbon can be comprised of alkyl, alkene, alkyne, aryl, and/orcycloalkyl, each can be substituted or unsubstituted, and can beinterrupted by one or more heteroatoms. The number of carbon atoms canrange from 2 to 20, and is preferably lower, e.g., from 1 to 10, or from1 to 6, or from 1 to 4. A hydrocarbon can be a linking group or an endgroup.

Bisphenol A is An example of a hydrocarbon comprised of 2 aryl groupsand one alkyl group.

As used herein, the term “amine” describes both a —NR′R″ group and a—NR′— group, wherein R′ and R″ are each independently hydrogen, alkyl,cycloalkyl, aryl, as these terms are defined hereinbelow.

The amine group can therefore be a primary amine, where both R′ and R″are hydrogen, a secondary amine, where R′ is hydrogen and R″ is alkyl,cycloalkyl or aryl, or a tertiary amine, where each of R′ and R″ isindependently alkyl, cycloalkyl or aryl.

Alternatively, R′ and R″ can each independently be hydroxyalkyl,trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl,heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate,hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano,nitro, azo, sulfonamide, carbonyl, C-carboxylate, O-carboxylate,N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate,O-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine.

The term “amine” is used herein to describe a —NR′R″ group in caseswhere the amine is an end group, as defined hereinunder, and is usedherein to describe a —NR′— group in cases where the amine is a linkinggroup or is or part of a linking moiety.

The term “alkyl” describes a saturated aliphatic hydrocarbon includingstraight chain and branched chain groups. Preferably, the alkyl grouphas 1 to 20 carbon atoms. Whenever a numerical range; e.g., “1-20”, isstated herein, it implies that the group, in this case the alkyl group,may contain 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., up toand including 20 carbon atoms. More preferably, the alkyl is a mediumsize alkyl having 1 to 10 carbon atoms. Most preferably, unlessotherwise indicated, the alkyl is a lower alkyl having 1 to 4 carbonatoms (C(1-4) alkyl). The alkyl group may be substituted orunsubstituted. Substituted alkyl may have one or more substituents,whereby each substituent group can independently be, for example,hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl,heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide,phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy,thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate,O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea,N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine andhydrazine.

The alkyl group can be an end group, as this phrase is definedhereinabove, wherein it is attached to a single adjacent atom, or alinking group, as this phrase is defined hereinabove, which connects twoor more moieties via at least two carbons in its chain. When the alkylis a linking group, it is also referred to herein as “alkylene” or“alkylene chain”.

Alkene (or alkenyl) and Alkyne (or alkynyl), as used herein, are analkyl, as defined herein, which contains one or more double bond ortriple bond, respectively.

The term “cycloalkyl” describes an all-carbon monocyclic ring or fusedrings (i.e., rings which share an adjacent pair of carbon atoms) groupwhere one or more of the rings does not have a completely conjugatedpi-electron system. Examples include, without limitation, cyclohexane,adamantine, norbornyl, isobornyl, and the like. The cycloalkyl group maybe substituted or unsubstituted. Substituted cycloalkyl may have one ormore substituents, whereby each substituent group can independently be,for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl,aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide,phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy,thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate,O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea,N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine andhydrazine. The cycloalkyl group can be an end group, as this phrase isdefined hereinabove, wherein it is attached to a single adjacent atom,or a linking group, as this phrase is defined hereinabove, connectingtwo or more moieties at two or more positions thereof.

The term “heteroalicyclic” describes a monocyclic or fused ring grouphaving in the ring(s) one or more atoms such as nitrogen, oxygen andsulfur. The rings may also have one or more double bonds. However, therings do not have a completely conjugated pi-electron system.Representative examples are piperidine, piperazine, tetrahydrofuran,tetrahydropyrane, morpholine, oxalidine, and the like. Theheteroalicyclic may be substituted or unsubstituted. Substitutedheteroalicyclic may have one or more substituents, whereby eachsubstituent group can independently be, for example, hydroxyalkyl,trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl,heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate,hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano,nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate,O-thiocarbamate, urea, thiourea, O-carbamate, N-carbamate, C-amide,N-amide, guanyl, guanidine and hydrazine. The heteroalicyclic group canbe an end group, as this phrase is defined hereinabove, where it isattached to a single adjacent atom, or a linking group, as this phraseis defined hereinabove, connecting two or more moieties at two or morepositions thereof.

The term “aryl” describes an all-carbon monocyclic or fused-ringpolycyclic (i.e., rings which share adjacent pairs of carbon atoms)groups having a completely conjugated pi-electron system. The aryl groupmay be substituted or unsubstituted. Substituted aryl may have one ormore substituents, whereby each substituent group can independently be,for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl,aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide,phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy,thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate,O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea,N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine andhydrazine. The aryl group can be an end group, as this term is definedhereinabove, wherein it is attached to a single adjacent atom, or alinking group, as this term is defined hereinabove, connecting two ormore moieties at two or more positions thereof.

The term “heteroaryl” describes a monocyclic or fused ring (i.e., ringswhich share an adjacent pair of atoms) group having in the ring(s) oneor more atoms, such as, for example, nitrogen, oxygen and sulfur and, inaddition, having a completely conjugated pi-electron system. Examples,without limitation, of heteroaryl groups include pyrrole, furan,thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine,quinoline, isoquinoline and purine. The heteroaryl group may besubstituted or unsubstituted. Substituted heteroaryl may have one ormore substituents, whereby each substituent group can independently be,for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl,aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide,phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy,thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate,O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea,O-carbamate, N-carbamate, C-amide, N-amide, guanyl, guanidine andhydrazine. The heteroaryl group can be an end group, as this phrase isdefined hereinabove, where it is attached to a single adjacent atom, ora linking group, as this phrase is defined hereinabove, connecting twoor more moieties at two or more positions thereof. Representativeexamples are pyridine, pyrrole, oxazole, indole, purine and the like.

The term “cyclic ring” encompasses a cycloalkyl, a heteroalicyclic, anaryl (an aromatic ring) and a heteroaryl (a heteroaromatic ring).

The term “halide” and “halo” describes fluorine, chlorine, bromine oriodine.

The term “haloalkyl” describes an alkyl group as defined above, furthersubstituted by one or more halide.

The term “sulfate” describes a —O—S(═O)₂—OR′ end group, as this term isdefined hereinabove, or an —O—S(═O)₂—O— linking group, as these phrasesare defined hereinabove, where R′ is as defined hereinabove.

The term “thiosulfate” describes a —O—S(═S)(═O)—OR′ end group or a—O—S(═S)(═O)—O— linking group, as these phrases are defined hereinabove,where R′ is as defined hereinabove.

The term “sulfite” describes an —O—S(═O)—O—R′ end group or a —O—S(═O)—O—group linking group, as these phrases are defined hereinabove, where R′is as defined hereinabove.

The term “thiosulfite” describes a —O—S(═S)—O—R′ end group or an—O—S(═S)—O— group linking group, as these phrases are definedhereinabove, where R′ is as defined hereinabove.

The term “sulfinate” describes a —S(═O)—OR′ end group or an —S(═O)—O—group linking group, as these phrases are defined hereinabove, where R′is as defined hereinabove.

The term “sulfoxide” or “sulfinyl” describes a —S(═O)R′ end group or an—S(═O)— linking group, as these phrases are defined hereinabove, whereR′ is as defined hereinabove.

The term “sulfonate” describes a —S(═O)₂—R′ end group or an —S(═O)₂—linking group, as these phrases are defined hereinabove, where R′ is asdefined herein.

The term “S-sulfonamide” describes a —S(═O)₂—NR′R″ end group or a—S(═O)₂—NR′— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “N-sulfonamide” describes an R'S(═O)₂—NR″— end group or a—S(═O)₂—NR′— linking group, as these phrases are defined hereinabove,where R′ and R″ are as defined herein.

The term “disulfide” refers to a —S—SR′ end group or a —S—S— linkinggroup, as these phrases are defined hereinabove, where R′ is as definedherein.

The term “oxo” as used herein, describes a (═O) group, wherein an oxygenatom is linked by a double bond to the atom (e.g., carbon atom) at theindicated position.

The term “thiooxo” as used herein, describes a (═S) group, wherein asulfur atom is linked by a double bond to the atom (e.g., carbon atom)at the indicated position.

The term “oxime” describes a ═N—OH end group or a ═N—O— linking group,as these phrases are defined hereinabove.

The term “hydroxyl” describes a —OH group.

The term “alkoxy” describes both an —O-alkyl and an —O-cycloalkyl group,as defined herein.

The term “aryloxy” describes both an —O-aryl and an —O-heteroaryl group,as defined herein.

The term “thiohydroxy” describes a —SH group.

The term “thioalkoxy” describes both a —S-alkyl group, and a—S-cycloalkyl group, as defined herein.

The term “thioaryloxy” describes both a —S-aryl and a —S-heteroarylgroup, as defined herein.

The “hydroxyalkyl” is also referred to herein as “alcohol”, anddescribes an alkyl, as defined herein, substituted by a hydroxy group.

The term “cyano” describes a —C≡N group.

The term “cyanurate” describes a

end group or

linking group, with R′ and R″ as defined herein.

The term “isocyanurate” describes a

end group or

a linking group, with R′ and R″ as defined herein.

The term “thiocyanurate” describes a

end group or

linking group, with R′ and R″ as defined herein.

The term “isocyanate” describes an —N═C═O group.

The term “isothiocyanate” describes an —N═C═S group.

The term “nitro” describes an —NO₂ group.

The term “acyl halide” describes a —(C═O)R″″ group wherein R″″ ishalide, as defined hereinabove.

The term “azo” or “diazo” describes an —N═NR′ end group or an —N═N—linking group, as these phrases are defined hereinabove, with R′ asdefined hereinabove.

The term “peroxo” describes an —O—OR′ end group or an —O—O— linkinggroup, as these phrases are defined hereinabove, with R′ as definedhereinabove.

The term “carboxylate” as used herein encompasses C-carboxylate andO-carboxylate.

The term “C-carboxylate” describes a —C(═O)—OR′ end group or a —C(═O)—O—linking group, as these phrases are defined hereinabove, where R′ is asdefined herein.

The term “O-carboxylate” describes a —OC(═O)R′ end group or a —OC(═O)—linking group, as these phrases are defined hereinabove, where R′ is asdefined herein.

A carboxylate can be linear or cyclic. When cyclic, R′ and the carbonatom are linked together to form a ring, in C-carboxylate, and thisgroup is also referred to as lactone. Alternatively, R′ and O are linkedtogether to form a ring in O-carboxylate. Cyclic carboxylates canfunction as a linking group, for example, when an atom in the formedring is linked to another group.

The term “thiocarboxylate” as used herein encompasses C-thiocarboxylateand O-thiocarboxylate.

The term “C-thiocarboxylate” describes a —C(═S)—OR′ end group or a—C(═S)—O— linking group, as these phrases are defined hereinabove, whereR′ is as defined herein.

The term “O-thiocarboxylate” describes a —OC(═S)R′ end group or a—OC(═S)— linking group, as these phrases are defined hereinabove, whereR′ is as defined herein.

A thiocarboxylate can be linear or cyclic. When cyclic, R′ and thecarbon atom are linked together to form a ring, in C-thiocarboxylate,and this group is also referred to as thiolactone. Alternatively, R′ andO are linked together to form a ring in O-thiocarboxylate. Cyclicthiocarboxylates can function as a linking group, for example, when anatom in the formed ring is linked to another group.

The term “carbamate” as used herein encompasses N-carbamate andO-carbamate.

The term “N-carbamate” describes an R″OC(═O)—NR′— end group or a—OC(═O)—NR′— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “O-carbamate” describes an —OC(═O)—NR′R″ end group or an—OC(═O)—NR′— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

A carbamate can be linear or cyclic. When cyclic, R′ and the carbon atomare linked together to form a ring, in O-carbamate. Alternatively, R′and O are linked together to form a ring in N-carbamate. Cycliccarbamates can function as a linking group, for example, when an atom inthe formed ring is linked to another group.

The term “carbamate” as used herein encompasses N-carbamate andO-carbamate.

The term “thiocarbamate” as used herein encompasses N-thiocarbamate andO-thiocarbamate.

The term “O-thiocarbamate” describes a —OC(═S)—NR′R″ end group or a—OC(═S)—NR′— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “N-thiocarbamate” describes an R″OC(═S)NR′— end group or a—OC(═S)NR′— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

Thiocarbamates can be linear or cyclic, as described herein forcarbamates.

The term “dithiocarbamate” as used herein encompasses S-dithiocarbamateand N-dithiocarbamate.

The term “S-dithiocarbamate” describes a —SC(═S)—NR′R″ end group or a—SC(═S)NR′— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “N-dithiocarbamate” describes an R″SC(═S)NR′— end group or a—SC(═S)NR′— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “urea”, which is also referred to herein as “ureido”, describesa —NR′C(═O)—NR″R′″ end group or a —NR′C(═O)—NR″— linking group, as thesephrases are defined hereinabove, where R′ and R″ are as defined hereinand R′″ is as defined herein for R′ and R″.

The term “thiourea”, which is also referred to herein as “thioureido”,describes a —NR′—C(═S)—NR″R′″ end group or a —NR′—C(═S)—NR″— linkinggroup, with R′, R″ and R′″ as defined herein.

The term “amide” as used herein encompasses C-amide and N-amide.

The term “C-amide” describes a —C(═O)—NR′R″ end group or a —C(═O)—NR′—linking group, as these phrases are defined hereinabove, where R′ and R″are as defined herein.

The term “N-amide” describes a R′C(═O)—NR″— end group or a R′C(═O)—N—linking group, as these phrases are defined hereinabove, where R′ and R″are as defined herein.

An amide can be linear or cyclic. When cyclic, R′ and the carbon atomare linked together to form a ring, in C-amide, and this group is alsoreferred to as lactam.

Cyclic amides can function as a linking group, for example, when an atomin the formed ring is linked to another group.

The term “guanyl” describes a R′R″NC(═N)— end group or a —R′NC(═N)—linking group, as these phrases are defined hereinabove, where R′ and R″are as defined herein.

The term “guanidine” describes a —R′NC(═N)—NR″R′″ end group or a—R′NC(═N)— NR″— linking group, as these phrases are defined hereinabove,where R′, R″ and R′″ are as defined herein.

The term “hydrazine” describes a —NR′—NR″R′″ end group or a—NR′—NR″-linking group, as these phrases are defined hereinabove, withR′, R″, and R′″ as defined herein.

As used herein, the term “hydrazide” describes a —C(═O)—NR′—NR″R′″ endgroup or a —C(═O)—NR′—NR″— linking group, as these phrases are definedhereinabove, where R′, R″ and R″ are as defined herein.

As used herein, the term “thiohydrazide” describes a —C(═S)—NR′—NR″R′″end group or a —C(═S)—NR′—NR″— linking group, as these phrases aredefined hereinabove, where R′, R″ and R″ are as defined herein.

As used herein, the term “alkylene glycol” describes a—O—[(CR′R″)_(z)—O]_(y)—R′″ end group or a —O—[(CR′R″)_(z)—O]_(y)—linking group, with R′, R″ and R′″ being as defined herein, and with zbeing an integer of from 1 to 10, preferably, 2-6, more preferably 2 or3, and y being an integer of 1 or more. Preferably R′ and R″ are bothhydrogen. When z is 2 and y is 1, this group is ethylene glycol. When zis 3 and y is 1, this group is propylene glycol.

When y is greater than 4, the alkylene glycol is referred to herein aspoly(alkylene glycol). In some embodiments of the present invention, apoly(alkylene glycol) group or moiety can have from 10 to 200 repeatingalkylene glycol units, such that z is 10 to 200, preferably 10-100, morepreferably 10-50.

The term “silyl” describes a —SiR′R″R′″ end group or a —SiR′R″— linkinggroup, as these phrases are defined hereinabove, whereby each of R′, R″and R′″ are as defined herein.

The term “siloxy” describes a —Si(OR′)R″R′″ end group or a—Si(OR′)R″-linking group, as these phrases are defined hereinabove,whereby each of R′, R″ and R′″ are as defined herein.

The term “silaza” describes a —Si(NR′R″)R′″ end group or a —Si(NR′R″)—linking group, as these phrases are defined hereinabove, whereby each ofR′, R″ and R′″ is as defined herein.

The term “silicate” describes a —O—Si(OR′)(OR″)(OR′″) end group or a—O—Si(OR′)(OR″)— linking group, as these phrases are definedhereinabove, with R′, R″ and R′″ as defined herein.

The term “boryl” describes a —BR′R″ end group or a —BR′— linking group,as these phrases are defined hereinabove, with R′ and R″ are as definedherein. The term “borate” describes a —O—B(OR′)(OR″) end group or a—O—B(OR′)(O—) linking group, as these phrases are defined hereinabove,with R′ and R″ are as defined herein.

As used herein, the term “epoxide” describes a

end group or a

linking group, as these phrases are defined hereinabove, where R′, R″and R′″ are as defined herein.

As used herein, the term “methyleneamine” describes an—NR′—CH₂—CH═CR″R′″ end group or a —NR′—CH₂—CH═CR″— linking group, asthese phrases are defined hereinabove, where R′, R″ and R′″ are asdefined herein.

The term “phosphonate” describes a —P(═O)(OR′)(OR″) end group or a—P(═O)(OR′)(O)— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “thiophosphonate” describes a —P(═S)(OR′)(OR″) end group or a—P(═S)(OR′)(O)— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “phosphinyl” describes a —PR′R″ end group or a —PR′— linkinggroup, as these phrases are defined hereinabove, with R′ and R″ asdefined hereinabove.

The term “phosphine oxide” describes a —P(═O)(R′)(R″) end group or a—P(═O)(R′)— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “phosphine sulfide” describes a —P(═S)(R′)(R″) end group or a—P(═S)(R′)— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “phosphite” describes an —O—PR′(═O)(OR″) end group or an—O—PH(═O)(O)— linking group, as these phrases are defined hereinabove,with R′ and R″ as defined herein.

The term “carbonyl” or “carbonate” as used herein, describes a —C(═O)—R′end group or a —C(═O)— linking group, as these phrases are definedhereinabove, with R′ as defined herein. This term encompasses ketonesand aldehydes.

The term “thiocarbonyl” as used herein, describes a —C(═S)—R′ end groupor a —C(═S)— linking group, as these phrases are defined hereinabove,with R′ as defined herein.

The term “oxime” describes a=N—OH end group or a=N—O— linking group, asthese phrases are defined hereinabove.

Other chemical groups are to be regarded according to the commondefinition thereof in the art and/or in line of the definitions providedherein.

Various embodiments and aspects of the present invention as delineatedhereinabove and as claimed in the claims section below find experimentalsupport in the following examples.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions illustrate some embodiments of the invention in a nonlimiting fashion.

Experimental Methods

Thermo-mechanical properties of the polymerized material were determinedby measuring the impact strength and HDT according to respective ASTMprocedures, as follows:

The impact strength of polymerized (cured) materials was measured by aResil 5.5 J type instrument (CEAST Series, Instron® (USA)) using an Izodimpact test (notched Izod) according to the ASTM Internationalorganization D-256 standard.

The Heat deflection temperature (HDT) of the samples was determinedaccording to the ASTM International organization D-648 standard using aHDT 3 VICAT instrument (CEAST Series, Instron® (USA)).

Example 1 Single Jetting and Single or Dual Curing

Table 3 below presents exemplary components usable in a single jettingmethodology according to some embodiments of the present invention. Dualcuring can be selected by including in the formulation monomers otherthan ROMP monomers or by including one or more of the dual-curingROMP-UV monomers (as shaded in grey in Table 3). Single curing includesonly ROMP monomers, in any combination.

TABLE 3 Optional Trade Name Chemical Name Function Supplier ULTRENE ™ 99Dicyclopentadiene ROMP bifunctional Cymetech DCPD Monomer (Cross-linker) ULTRENE ™ 99-X Cyclopentadiene trimer in ROMP bifunctionalCymetech DCPD (X = 6-20%) dicyclopentadiene Monomer (Cross- linker)Cyclopentadiene Cyclopentadiene trimer ROMP bifunctional SinosteelAnshan trimer Monomer (Cross- Research linker) Institute ofthermo-energy Cyclooctene Cyclooctene ROMP Monomer Sigma AldrichCyclooctadiene Cyclooctadiene ROMP Monomer Sigma Aldrich Norbornene ROMPMonomer Cyclododecatriene Cyclododecatriene ROMP Monomer BASF FA-512ASDicyclopentadienyloxyethylacrylate ROMP-UV Hitachi dual-curing monomerchemicals FA-511AS Dicyclopentadieny acrylate ROMP-UV Hitachidual-curing monomer chemicals Kraton no. 1102 Styrene-butadiene-styrenerubber GLS rubber Trilene Liquid EPDM rubber Lion copolymers RICONEpoxydized poly butadiene rubber Cray Valley Polybutadiene rubberLanexss Vistalon Ethylene propylene diene rubber ExonMobile (EPDM)rubber chemicals PolyBD 605E Epoxidized hydroxyl Epoxy polymer CrayValley terminated polybutadiene resin (multifunctional; cross-linker) SR833S Cycloaliphatic diacrylate Acrylate monomer Sartomer (bifunctional;cross- linker) SR 423 IBOMA Methacrylate Sartomer monomer Exactplastomers Rubber-plastic ExonMobile chemicals Ethanox 7024,4′-Methylenebis(2,6-di-tert- antioxidant Albemarle butylphenol) Grubbs1^(st) Benzylidene- ROMP catalyst Materia generation catalystbis(tricyclohexylphosphine)- dichlororuthenium Grubbs 2^(st)[1,3-bis-(2,4,6-trimethylphenyl)- ROMP catalyst Materia generationcatalysts 2-imidazolidinylidene]dichlor-o(phenylmethylene)(tricyclohexyl- phosphine)ruthenium Hoveyda-Grubbs1^(st) Dichloro(o-isopropoxyphenyl ROMP catalyst Materia GenerationCatalyst methylene)(tricyclohexylphos- phine)ruthenium(II)Hoveyda-Grubbs [1,3-Bis-(2,4,6-trimethylphenyl)- ROMP catalyst Materia2^(nd) Generation 2-imidazolidinylidene]dichloro(o- Catalystisopropoxyphenylmethylene)ru- thenium Umicore 41 [1,3-Bis(mesityl)-2-ROMP catalyst Umicore imidazolidinyl-idene]-[2-[[(4- methylphenyl)imin-o]methyl]-4-nitro-phenolyl]-[3- phenyl-indenylidene](chloro)ru-thenium(II) Umicore 42 [1,3-Bis(mesityl)-2- ROMP catalyst Umicoreimidazolidinylidene]- [2-[[(2-methylphenyl)imin- o]methyl]-phenolyl]-[3-phenyl-indenyliden](chlor- o)ruthenium(II) Umicore 22cis-[1,3-Bis(2,4,6- ROMP catalyst Umicoretrimethylphenyl)-2-imidazolidin- ylidene]dichloro(3-phenyl-1H-inden-1-ylidene) (triisopropyl- phosphite)ruthenium(II) Umicore 21,3-Bis(2,4,6-trimethylphenyl)-2- ROMP catalyst Umicoreimidazolidinylidene] dichloro(3- phenyl-1H-inden-1-ylidene)(tri-cyclohexylphosphine)ruthenium(II) Umicore 61[1,3-Bis(2,4,6-trimethylphenyl)- ROMP catalyst Umicore2-imidazolidinylidene]dichloro[2- methyl(phenyl)amino]benzyli-dene]ruthenium(II) Triphenyl Triphenyl phosphine ROMP inhibitor SigmaAldrich phosphine Triethylphosphite Triethylphosphite ROMP inhibitorSigma Aldrich Trimethylphosphite Trimethylphosphite ROMP inhibitor SigmaAldrich tributylphosphite Tributylphosphite ROMP inhibitor Sigma AldrichIrgacure PAG103 Photoacid generator BASF (PAG) Irgacure PAG121 Photoacidgenerator BASF (PAG) Trichloro(phenyl)silane Trichloro(phenyl)silaneChemically-activated Aldrich Acid generator -(4-Methoxystyryl)-4,6-Photoacid generator TCI bis(trichloromethyl)- (PAG) 1,3,5-triazine TMCHPhotoacid generator (PAG) Triphenyl sulfonium Photoacid generator SigmaAldrich chloride (PAG)

In exemplary embodiments of a single jetting single curing approach, amodeling material formulation comprises one or more of the ROMP monomerslisted in Table 3 and one or more of the ROMP catalysts listed in Table3. Depending on the selected catalyst, one or more of the ROMPinhibitors and/or one or more of the acid generators are also included.Optionally, and for the purpose of modifying mechanical and/or physicalproperties, one or more of the rubbers and/or epoxy resins are alsoincluded. Further optionally, an antioxidant such as listed in Table 3is included.

Table 4 below presents a representative, non-limiting example of amodeling material formulation suitable for use in a single jettingsingle curing approach.

TABLE 4 Component Chemical name Function X Y DCPD ROMP X X MonomerGrubbs 2^(st) [1,3-bis-(2,4,6-trimethylphenyl)-2- ROMP X generationimidazolidinylidene]dichloro(phenyl- catalyst catalystsmethylene)(tricyclohexylphos- phine)ruthenium Triphenyl Triphenylphosphine ROMP X phosphine inhibitor pyridine ROMP X inhibitor

In exemplary embodiments of a single jetting dual curing approach, oneor more of the acrylate or methacrylate UV-curable monomers and/or oneor more of the ROMP-UV curable monomers are also included in aformulation as described hereinabove.

Table 5 below presents an exemplary, non-limiting modeling materialformulation usable in embodiments pertaining to a single jettingmethodology, with formulations A, B C and E are representative forsingle curing approach and formulation D for dual curing.

TABLE 5 Component (Trade name) Function A B C D E ULTRENE ™ ROMPmonomer-DCPD X X 99 DCPD ULTRENE ™ ROMP monomer-DCPD (88.8%) X X X 99-XDCPD TCPD (10.9%) SR 833S Acrylic monomer (bifunctional) X X PolyBD605EEpoxidized polybutadiene X (bifunctional) SR 423 Methacrylic monomer XPhoto- ROMP latent catalyst X X X X X activatable catalyst

The photoactivatable catalyst is described in Beilsten J. Org. Chem.,2010, 6, 1106-1119.

Table 6 presents the mechanical properties of the formulations presentedin Table 5 upon curing a molded formulation.

TABLE 6 Mechanical properties A B C D E Impact (J/m) 92.1 94 157 80 157HDT (° C.) 93.2 87 54 150 55 Post curing 2 hours 5 hours 1.5 hours 5hours 5 hours conditions at 85° C. at 70° C. at 140° C. at 70° C. at 70°C.

Table 7 below presents non-limiting, exemplary modeling materialformulations containing an acid-activatable catalyst, a photoacidgenerator (PAG) and a photosensitizer. Usable acid-activatable catalystsinclude, for example, those described in U.S. Pat. No. 6,486,279; WO99/22865; and U.S. Patent Application having Publication No. US2012/0271019, all of which are incorporated by reference as if fully setforth herein.

TABLE 7 Component Function F G DCPD ROMP Monomer X X (bifunctional;cross linker) CPD oligomers ROMP Monomer X X (bifunctional; crosslinker) Trilene77 Rubber X X Acid-activatable catalyst Pre-catalyst X X2-(4-Methoxystyryl)-4,6- PAG (photo activator) X Xbis(trichloromethyl)-1,3,5-triazine ITX Photosensitizer X

Example 2 Dual Jetting, Single or Dual Curing

Tables 8, 9 and 10 below present exemplary components usable in a dualjetting methodology according to some embodiments of the presentinvention.

Table 8 below presents exemplary ROMP polymerizable monomers usable fora dual jetting single curing approach as described herein, and theproperties of an object obtainable when these monomers co-polymerize ina mold, as described in the art (see, for example,www(dot)metton(dot)com/index(dot)php/metton-lmr/benefits).

TABLE 8 Formu- Impact Tg lation Component Function (J/m)* (° C.)* IMetton LMR ROMP 460 >135 M15xx monomer II Metton ROMP 400 ND M2100VOmonomer

In exemplary embodiments, two modeling material formulations, I and II,are employed, each comprising a ROMP monomer as shown in Table 8. One ofthe formulations comprises a ROMP pre-catalyst and the other formulationcomprises a suitable activator.

Table 9 below presents exemplary modeling material formulations whichare usable in the context of embodiments of the present invention,pertaining to a dual jetting dual curing approach. Formulation Model Iincludes one or more ROMP monomers and a photoinitiator for cationicpolymerization, and optionally a rubber, and Formulation Model IIincludes epoxy monomers (polymerizable via cationic polymerization) andan activatable catalyst for ROMP.

TABLE 9 Formulation Component Function A B Model I DCPD ROMP Monomer X X(bifunctional; crosslinker) CPD oligomers ROMP Monomer X X(bifunctional; crosslinker) Trilene77 rubber X X UVACURE1600 CationicPhotoinitiator X X Model II ITX Photo-sensitizer X X UVACURE1500 Epoxymonomer X Celloxide 8000 Epoxy monomer X Genorad 20 Stabilizer X XGrubbs 2^(nd) Gen ROMP active catalyst X X

Table 10 below presents the properties of an object obtainable upon dualcuring of formulations I and II presented in Table 9, used at weightratio of 70:30 (I:II).

TABLE 10 Mechanical properties A B Impact (J/m) 60 67 HDT (° C.) 90 93Post curing conditions 2 h at 150° C. 2 h at 150° C.

Additional, non-limiting exemplary modeling material formulationssuitable for use in a dual jetting dual curing approach according tosome embodiments of the invention are shown in Table 11.

TABLE 11 Component (Trade name) Function Model I Model II ULTRENE ™ 99DCPD (ROMP) X DCPD monomer Uvacure 1600 Cationic photoinitiator XUvacure 1500 Cycloaliphaticepoxide X (UV-curable monomer) Grubbs 2^(nd)Gen ROMP catalyst X

Table 12 below presents the mechanical properties of objects preparedusing the modeling material formulations presented in Table 11.

TABLE 12 Mechanical properties Impact (J/m) 65 HDT (° C.) 63 Post curingconditions 2 h at 85° C.

Additional, non-limiting exemplary modeling material formulationssuitable for use in a dual jetting dual curing approach according tosome embodiments of the invention are shown in Table 13.

TABLE 13 Component (Trade name) Function Model I Model II ULTRENE ™ 99DCPD (ROMP) monomer X DCPD Irgacure I-819 Radical photoinitiator XFancryl FA512 Dicyclopentadienyloxyethyl X acrylate (UV-curable monomer)Grubbs 2^(nd) Gen ROMP catalyst X

Table 14 below presents the mechanical properties of objects preparedusing the modeling material formulations presented in Table 13.

TABLE 14 Mechanical properties Impact (J/m) 72 HDT (° C.) 73 Post curingconditions 5 h at 70° C.

Example 3 Toughening Agents

Preliminary experiments were performed for assessing the effect ofvarious elastomeric materials on the mechanical properties (Impactresistance, HDT) of cured ROMP materials. All tested formulationsinclude a mixture of DCPD and a CPD trimer as a ROMP monomer, and a ROMPcatalyst.

Tested elastomeric materials were all hydrophobic, and were selected assuch for assuring sufficient dissolvability or dispersability in theformulation.

Table 15 below presents the mechanical properties of the obtained curedmaterials.

TABLE 15 Concen- Elastomer Chemical tration Impact HDT Trade namestructure Mw (% wt.) (J/m) (° C.) No elastomer — — 0 78 142 IndopolH-18000 Polybutene  10 kDa 6 382 144 Indopol H-6000 Polybutene   7 kDa 8330 144 Kuraray L-BR-307 Polybutadiene   8 kDa 8 69 151 Trilene CP 1100*EPR 6.6 kDa 8 130 142 Trilene CP 1100* EPR 6.6 kDa 6 100 146 Trilene CP1100* EPR 6.6 kDa 4 212 142 Trilene CP80** EPR  23 kDa 5 302 151 Trilene67** EPDM  39 kDa 3.6 209 140 Trilene 77** EPDM  27 kDa 5 450 128*Jettability of the formulation in a 3D inkjet printing system was good**Jettability of the formulation in a 3D inkjet printing system was notcontinuous

The data presented in Table 15 suggests the following:

While high molecule weight elastomers such as an EPDM elastomer provideexceptional mechanical properties, such elastomers are less suitable for3D inkjet printing applications due to jetting instability. Lowmolecular weight elastomers with unsaturated backbone, on the otherhand, provide substantially inferior mechanical properties, with theImpact resistance being lower than the control (without elastomer).Without being bound by any particular theory, it is assumed that suchlow molecular weight elastomers participate in the olefin metathesis,and hence their effect on the mechanical properties is less pronounced.

Low molecular weight elastomers which include saturated backbone, andhence are not expected to participate in olefin metathesis, provide forimproved Impact resistance compared to the control, and are typicallyfurther characterized by good jettability, and hence may be suitable for3D inkjet printing.

Without being bound by any particular theory, it is suggested that inorder to obtain a toughening and/or impact modifying effect, phaseseparation should be effected in the cured material.

It is therefore suggested that a suitable elastomeric material should besufficiently hydrophobic so as to be dissolvable or dispersible in theuncured formulation, yet should not form a part of the polymeric matrixforming the cured modeling material, that is, should be capable offorming a multiphasic (e.g., biphasic) structure when blended with thecured material, as discussed herein.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

It is the intent of the applicant(s) that all publications, patents andpatent applications referred to in this specification are to beincorporated in their entirety by reference into the specification, asif each individual publication, patent or patent application wasspecifically and individually noted when referenced that it is to beincorporated herein by reference. In addition, citation oridentification of any reference in this application shall not beconstrued as an admission that such reference is available as prior artto the present invention. To the extent that section headings are used,they should not be construed as necessarily limiting. In addition, anypriority document(s) of this application is/are hereby incorporatedherein by reference in its/their entirety.

What is claimed is:
 1. A method of fabricating a three-dimensionalobject, the method comprising sequentially forming a plurality of layersin a configured pattern corresponding to the shape of the object,thereby forming the object, wherein said formation of each layercomprises: dispensing by at least two inkjet printing head nozzle arraysat least two modeling material formulations, each nozzle array jettingone of said at least two modeling material formulations, wherein atleast one of said at least two modeling material formulations comprisesan unsaturated cyclic monomer polymerizable by ring opening metathesispolymerization (ROMP), at least one of said at least two modelingmaterial formulations comprises a catalyst for initiating ROMP of saidmonomer, at least one of said at least two of said modeling materialformulations comprises at least one material polymerizable or curablevia a non-ROMP reaction, and at least one of said at least two modelingmaterial formulations further comprises a toughening agent; and exposingthe dispensed at least two modeling material formulations to a conditionfor inducing initiation of ROMP of said unsaturated cyclic monomerpolymerizable by ROMP by said catalyst for initiating ROMP of saidmonomer and to a condition for inducing polymerization or curing of saidat least one material polymerizable or curable via a non-ROMP reaction,to thereby obtain a cured modeling material, wherein said tougheningagent is or comprises an elastomeric material characterized by at leastone of: a molecular weight lower than 30,000 Daltons; being non-reactivetowards ROMP; being dissolvable or dispersible in said at least onemodeling material formulation that comprises said toughening agent; andbeing capable of forming a multiphase structure when blended with saidcured modeling material.
 2. The method of claim 1, wherein saidelastomeric material is hydrophobic.
 3. The method of claim 1, whereinsaid elastomeric material is a saturated polymeric material.
 4. Themethod of claim 1, wherein said catalyst does not initiate ROMP of saidmonomer prior to exposing to said condition and is activatable uponexposing to said condition.
 5. The method of claim 4, wherein at leastone of said at least two modeling material formulations furthercomprises an activator for chemically activating said catalyst forinitiating ROMP towards initiating ROMP of said monomer polymerizable byROMP, wherein said activator is activatable upon exposure to saidcondition, such that exposing to said condition activates saidactivator, thereby activating said catalyst for initiating ROMP towardsinitiating ROMP of said monomer polymerizable by ROMP.
 6. The method ofclaim 4, wherein at least one of said at least two modeling materialformulations further comprises an activator for chemically activatingsaid catalyst for initiating ROMP towards initiating ROMP of saidmonomer polymerizable by ROMP, wherein one of said at least two modelingmaterial formulations comprises said unsaturated cyclic monomerpolymerizable by ROMP and said activator, and another one of said atleast two modeling material formulations comprises said catalyst forinitiating ROMP.
 7. The method of claim 4, wherein at least one of saidat least two modeling material formulations further comprises anactivator for chemically activating said catalyst for initiating ROMPtowards initiating ROMP of said monomer polymerizable by ROMP, whereinone of said at least two modeling material formulations comprises saidunsaturated cyclic monomer polymerizable by ROMP, and said catalyst forinitiating ROMP, and another one of said at least two modeling materialformulations comprises said activator.
 8. The method of claim 1, whereinsaid catalyst is active towards initiating ROMP of said unsaturatedcyclic monomer polymerizable by ROMP prior to exposing to saidcondition, and wherein one of said at least two modeling materialformulations comprises said unsaturated cyclic monomer polymerizable byring opening metathesis polymerization and is devoid of said catalystfor initiating ROMP of said monomer polymerizable by ROMP and anotherone of said at least two modeling material formulations comprises saidcatalyst for initiating ROMP of said monomer polymerizable by ROMP. 9.The method of claim 1, wherein said at least one material polymerizableor curable via a non-ROMP reaction comprises at least one material thatis a monomer and/or an oligomer polymerizable by free-radicalpolymerization, cationic polymerization, anionic polymerization, orpolycondensation.
 10. The method of claim 1, wherein said at least onematerial polymerizable or curable via a non-ROMP reaction and saidunsaturated cyclic monomer polymerizable by said ROMP are included inthe same modeling material formulation.
 11. The method of claim 1,wherein said at least one material polymerizable or curable by saidnon-ROMP reaction is comprised in at least one modeling materialformulation of said at least two modeling material formulations which isdevoid of said monomer polymerizable by said ROMP.
 12. The method ofclaim 1, wherein at least one of said at least two modeling materialformulations further comprises an initiator of said non-ROMP reaction.13. The method of claim 12, wherein said initiator is comprised in atleast one of said at least two modeling material formulations which isdevoid of said at least one material polymerizable or curable via saidnon-ROMP reaction.
 14. The method of claim 1, wherein said condition forinducing ROMP of said unsaturated cyclic monomer polymerizable by ROMPand said condition for inducing polymerization or curing of said atleast one material polymerizable or curable via a non-ROMP reaction arethe same.
 15. The method of claim 14, wherein at least one of said atleast two modeling material formulations comprises said monomerpolymerizable by ROMP and said initiator of said non-ROMP reaction andat least one other modeling material formulation of said at least twomodeling material formulations comprises said at least one materialpolymerizable or curable via a non-ROMP reaction and said catalyst forinitiating said ROMP.